Use any text editor (Notepad for example) and open the file Baldur.ini in your Baldur's Gate directory. Add the line Cheats=1 under the [Game Options] entry then save the file and run the game. Once in the game, hit Ctrl-Tab to bring up the console in which you type the cheats. Ctrl-Tab will also close this console. Type in the cheats exactly as they appear below and hit the Enter key to activate.

The list of cheats are as follows: 

Cheats:Hans() -- If you get stuck somehow this moves your characters to a free, adjacent area. 
Cheats:ExploreArea() -- Marks the entire area as explored 
Cheats:TheGreatGonzo() -- Summons 10 killer chickens who defend you at all cost. 
Cheats:CowKill() -- Creates a CowKill spell if you're near a cow. 
Cheats:CriticalItems() -- Spawns all the game critical items 
Cheats:DrizztAttacks() -- Creates a hostile Drizzt 
Cheats:DrizztDefends() -- Creates a friendly Drizzt 
Cheats:FirstAid() -- Creates 5 healing potions, 5 neutralize poison potions and 1 stone to flesh scroll. 
Cheats:Midas() -- Gives you 500 gold. 
CLUAConsole:CreateCreature("xxx") -- Summons a creature or NPC, where "xxx" is the name of any creature in the game. 
CLUAConsole:SetCurrentXP(###) -- Sets your experience to ###. 

Create Your Own Items  -  Use any text editor (Notepad for example) and open the file Baldur.ini in your Baldur's Gate directory. Add the line Cheats=1 under the [Game Options] entry then save the file and run the game. Once in the game, hit Ctrl-Tab to bring up the console in which you type the cheats. Ctrl-Tab will also close this console. Type in the cheat exactly as they appear below and hit the Enter key to activate.

CLUAConsole:CreateItem("xxx") where xxx is the code for an item:

AMUL01 - Necklace of Missiles
AMUL02 - Necklace
AMUL04 - Studded Necklace with Zios Gems
AMUL05 - Bluestone Necklace
AMUL06 - Agni Mani Necklace
AMUL07 - Rainbow Obsidian Necklace
AMUL08 - Tiger Cowrie Shell Necklace
AMUL09 - Silver Necklace
AMUL10 - Gold Necklace
AMUL11 - Pearl Necklace
AMUL12 - Laeral's Tear Necklace (3000 gp)
AMUL13 - Bloodstone Amulet
AMUL14 - Amulet of Protection +1
AMUL15 - Shield Amulet
AMUL16 - Amulet of Metaspell Influence (+1 2nd level spell)

AROW01 - Arrow
AROW02 - Arrow +1
AROW03 - Arrow of Slaying
AROW04 - Acid Arrow
AROW05 - Arrow of Biting
AROW06 - Arrow of Detonation
AROW07 - Arrow or Dispelling
AROW08 - Arrow of Fire
AROW09 - Arrow of Ice
AROW10 - Arrow of Piercing
AROW11 - Arrow +2
AROW1A - Arrow +2 (different picture)

AX1H01 - Battle Axe
AX1H02 - Battle Axe +1
AX1H03 - Battle Axe +2
AX1H04 - Throwing Axe
AX1H05 - Throwing Axe +2

BELT01 - Girdle
BELT02 - Golden Girdle
BELT03 - Girdle of Bluntness
BELT04 - Girdle of Piercing
BELT05 - Girdle of Sex Change

BLUN01 - Club
BLUN02 - Flail
BLUN03 - Flail +1
BLUN04 - Mace
BLUN05 - Mace +1
BLUN06 - Morning Star
BLUN07 - Morning Star +1
BLUN08 = Flail

BOLT01 - Bolt
BOLT02 - Bolt +1
BOLT03 - Bolt of Lightning
BOLT04 - Bolt of Biting
BOLT05 - Bolt of Polymorphing
BOLT06 - Bolt +2

BOOK01 - Magical Book
BOOK02 - Spell Book
BOOK03 - +1 Con
BOOK04 - +1 Str
BOOK05 - +1 Dex
BOOK06 - +1 Int
BOOK07 - +1 Chr
BOOK08 - +1 Wis
BOOK09 - Normal Book
BOOK10 through BOOK67 - miscellaneous Histories
BOOK68 = Book of Ancient Knowledge/History of the Nether Scrolls (must be Identified)
BOOK70 = Yago's Book of Curses

BOOT01 - Boots of Speed
BOOT02 - Boots of Stealth
BOOT03 - Boots of the North
BOOT04 - Boots of Avoidance
BOOT05 - Boots of Grounding

BOW01 - Composite Long Bow
BOW02 - Composite Long Bow +1
BOW03 - Long Bow
BOW04 - Long Bow +1
BOW05 - Short Bow
BOW06 - Short Bow +1
BOW07 - Long Bow of Marksmanship
BOW08 - Eagle Bow

BRAC01 - Bracers of Defense AC 8
BRAC02 - Bracers of Defense AC 7
BRAC03 - Bracers of Defense AC 6
BRAC04 - Bracers of Archery
BRAC05 - Bracers
BRAC06 - Gauntlets of Ogre Power
BRAC07 - Gauntlets of Dexterity
BRAC08 - Gauntlets of Fumbling
BRAC09 - Gauntlets of Weapon Skill
BRAC10 - Gauntlets of Weapon Expertise

BULL01 - Bullet
BULL02 - Bullet +1
BULL03 - Bullet +2

CHAN01 - Chainmail
CHAN02 - Chainmail +1
CHAN03 - Chainmail +2
CHAN04 - Splint Mail
CHAN05 - Splint Mail +1
CHAN06 - Mithril Chain Mail +4

CLCK01 - Cloak of Protection +1
CLCK02 - Cloak of Protection +2
CLCK03 - Cloak of Displacement
CLCK04 - Cloak of the Wolf
CLCK05 - Cloak of Balduran
CLCK06 - Cloak of Non-Detection
CLCK07 - Nymph Cloak
CLCK08 = Algernon's Cloak (+2 Charisma)
CLCK09 = Mage Robe of Cold Resistance
CLCK10 = Mage Robe of Fire Resistance
CLCK11 = Mage Robe of Electrical Resistance
CLCK12 = Knave's Robe
CLCK13 = Traveller's Robe
CLCK14 = Adventurer's Robe
CLCK15 = Robe of the Good Archmagi
CLCK16 = Robe of the Neutral Archmagi
CLCK17 = Robe of the Evil Archmagi
CLCK18 = Knave's Robe
CLCK19 = Robe of the Good Archmagi

DAGG01 - Dagger
DAGG02 - Dagger +1
DAGG03 - Dagger +2
DAGG04 - Dagger +2, Longtooth
DAGG05 - Throwing Dagger
DAGG06 = Nester's Dagger
DAGG07 = Kylee's Dagger
DAGG08 = Hentold's Dagger

DART01 - Dart
DART02 - Dart +1
DART03 - Dart of Stunning
DART04 - Dart of Wounding

HALB01 - Halberd
HALB02 - Halberd +1
HALB03 - Halberd +2

HAMM01 - War Hammer
HAMM02 - War Hammer +1
HAMM03 - War hammer +2

HELM01 - Helmet
HELM02 - Helm of Opposite Alignment
HELM03 - Helm of Glory
HELM04 - Helm of Defense
HELM05 - Helm of Infravision
HELM06 - Helm of Charm Protection
HELM07 - Helm of Balduran
HELM08 through HELM13 = Regular helmets, but several different pictures/styles

LEAT01 - Leather Armor
LEAT02 - Leather Armor +1
LEAT03 - Leather Armor +2
LEAT04 - Studded Leather Armor
LEAT05 - Studded Leather Armor +1
LEAT06 - Studded Leather Armor +2, missile attraction
LEAT07 - Studded Leather Armor +2
LEAT08 - Shadow Armor

MISC01 - Winter Wolf Pelt
MISC02 = Mirror (no picture)
MISC03 = Small Box (no picture)
MISC04 = Bassilus' Holy Symbol
MISC07 - Gold Piece
MISC12 - Ankheg Shell
MISC13 - Samuel (body)
MISC16 - Fire Agate Gem
MISC17 - Lynx Eye Gem
MISC18 - Sunstone Gem
MISC19 - Turquoise Gem
MISC20 - Bloodstone Gem
MISC21 - Skydrop Gem
MISC22 - Andar Gem
MISC23 - Jasper Gem
MISC24 - Tchazar Gem
MISC25 - Zircon Gem
MISC26 - Iol Gem
MISC27 - Moonstone Gem
MISC28 - Waterstar Gem
MISC29 - Ziose Gem
MISC30 - Chrysoberyl Gem
MISC31 - Star Diopside Gem
MISC32 - Shandon Gem
MISC33 - Aquamarine Gem
MISC34 - Garnet Gem
MISC35 - Horn Coral Gem
MISC36 - Pearl
MISC37 - Sphene Gem
MISC38 - Black Opal
MISC39 - Water Opal
MISC40 - Moonbar Gem
MISC41 - Star Sapphire
MISC42 - Diamond
MISC43 - Emerald
MISC44 - Kings Tears
MISC45 - Rogue Stone
MISC47 - Golden Pantaloons
MISC48 - Idol
MISC49 - Melicamp the Chicken
MISC50 - Skull
MISC51 - Lock of Nymph's Hair
MISC52 - Wyvern Head
MISC53 - Bowl of Water Elemental Control
MISC54 - Child's Body
MISC55 - Duke Eltan's Body
MISC56 - Broken Weapon
MISC57 - Broken Shield
MISC58 - Broken Armor
MISC59 - Broken Miscellaneous
MISC60 - Spider Body
MISC61 - Bottle of Wine
MISC62 - Dead Cat
MISC63 - Chew Toy
MISC64 - Telescope
MISC65 = Brage's Body
MISC66 = Farmer Brun's Son (Dead)
MISC67 = Brun's Dead Son
MISC68 = Abela the Nymph
MISC69 - Helshara's Artifact Fragment
MISC70 - Delorna's Statue
MISC71 = Delorna's Spellbook
MISC72 - The Claw of Kazgaroth
MISC73 - The Horn of Kazgaroth
MISC74 - The Candle
MISC75 = Dagger of Venom
MISC76 = The Dream Potion
MISC77 = Skull of Kereph
MISC78 = Invitation
MISC79 - Female Body
MISC80 - Male Body
MISC81 = Skull of Kereph
MISC82 = Ancient Armor
MISC83 - Key to River Plug
MISC84 - Boo
MISC85 - Mulahey's Holy Symbol
MISC86 - Bandit Scalp
MISC87 - Contaminated Iron
MISC88 - Rabbit's Foot
MISC89 = Edwin's Amulet
MISC90 = Chelak's Body
MISC99 = ? - Cursed Plate, looks like a belt, description from Spear +3 Backbiter

PLAT01 - Plate Mail Armor
PLAT02 - Plate Mail +1
PLAT04 - Full Plate Mail
PLAT05 - Full Plate Mail +1
PLAT06 - Ankheg Plate Mail
PLAT07 = Plate Mail

POTN02 - Potion of Fire Resistance
POTN03 - Potion of Hill Giant Strength
POTN04 - Potion of Frost Giant Strength
POTN05 - Potion of Fire Giant Strength
POTN06 - Potion of Cloud Giant Strength
POTN07 - Potion of Storm Giant Strength
POTN08 - Potion of Healing
POTN09 - Potion of Heroism
POTN10 - Potion of Invisibility
POTN11 - Potion of Invulnerability
POTN12 - Potion of Stone Giant Strength
POTN13 - Oil of Firey Burning
POTN14 - Oil of Speed
POTN15 - Red Potion
POTN16 - Violet Potion
POTN17 - Elixir of Health
POTN18 - Potion of Absorption
POTN19 - Potion of Agility
POTN20 - Antidote
POTN21 - Potion of Clarity
POTN22 - Potion of Cold Resistance
POTN23 - Oil of Speed
POTN24 - Potion of Defense
POTN25 - Potion of Healing
POTN26 - Potion of Explosions
POTN27 - Potion of Firebreath
POTN28 - Potion of Fortitude
POTN29 - Potion of Genius
POTN30 - Potion of Infravision
POTN31 - Potion of Insulation
POTN32 - Antidote
POTN33 - Potion of Magic Blocking
POTN34 - Potion of Magic Protection
POTN35 - Potion of Magic Shielding
POTN36 - Potion of Master Thievery
POTN37 - Potion of Mind Focusing
POTN38 - Potion of Mirrored Eyes
POTN39 - Potion of Perception
POTN40 - Potion of Invulnerability
POTN41 - Potion of Power
POTN42 - Potion of Regeneration
POTN43 - Potion of Insight
POTN44 - Potion of Strength
POTN45 - Potion of Freedom
POTN46 - Potion of Stone Form
POTN47 = Marek's Antidote (better than normal antidote)
POTN48 = Vial of Mysterious Liquid (used in Nashgel mines to poison iron ore)

RING01 - Ring
RING02 - Ring of Fire Resistance
RING03 - Ring of Animal Friendship
RING04 - Ring of Clumsiness
RING05 - Ring of Invisibility
RING06 - Ring of Protection +1
RING07 - Ring of Protection +2
RING08 - Ring of Wizardry
RING09 - Ring of Free Action
RING10 - Gold Ring
RING11 - Silver Ring
RING12 - Onyx Ring
RING13 - Jade Ring
RING14 - Greenstone Ring
RING15 - Bloodstone Ring
RING16 - Angel Skin Ring
RING17 - Flamedance Ring
RING18 - Fire Opal Ring
RING19 - Ruby Ring
RING20 - Ring of Energy
RING21 - Ring of Infravision
RING22 - Ring of Holiness
RING23 - Ring of Folly
RING25 = Koveras' Ring of Protection (+1)

SCRL02 - Spell Scroll
SCRL03 - Protection from Acid
SCRL04 - Protection from Cold
SCRL05 - Protection from Electricity
SCRL06 - Protection from Fire
SCRL07 - Protection from Magic
SCRL08 - Protection from Poison
SCRL09 - Protection from Undead
SCRL10 - Cursed Scroll of Weakness
SCRL11 = Cursed Scroll of Clumsiness
SCRL12 = Cursed Scroll of Foolishness
SCRL13 = Cursed Scroll of Ugliness
SCRL14 = Cursed Scroll of Summon Monster (casts Monster Summoning I)
SCRL15 - Protection from Petrification
SCRL18 - Cursed Scroll of Stupidity
SCRL1B - Agannazar's Scorcher
SCRL1C - Ghoul Touch
SCRL1D - Clairvoyance
SCRL1E - Dispel Magic
SCRL1F - Flame Arrow
SCRL1G - Fireball
SCRL1H - Haste
SCRL1I - Hold Person
SCRL1K - Lightning Bolt
SCRL1L - Monster Summoning I
SCRL1M - Non-Detection
SCRL1N - Protection from Normal Missiles
SCRL1O - Slow
SCRL1P - Skull Trap
SCRL1Q - Vampiric Touch
SCRL1R - Wraith Form
SCRL1S - Dire Charm
SCRL1T - Ghost Armor
SCRL1U - Confusion
SCRL1V - Dimension Door
SCRL1Y - Improved Invisibility
SCRL1Z - Minor Globe of Invulnerability
SCRL2A - Monster Summoning II
SCRL2D - Animate Dead
SCRL2E - Cloudkill
SCRL2F - Cone of Cold
SCRL2G - Monster Summoning III
SCRL2H - Shadow Door
SCRL2I - Letter
SCRL2J - Letter
SCRL3D - Letter
SCRL56 - Cure Serious Wounds
SCRL58 - Free Action
SCRL59 - Neutralize Poison
SCRL61 - Cure Critical Wounds
SCRL62 - Flame Strike
SCRL63 - Raise Dead
SCRL66 - Grease
SCRL67 - Armor
SCRL68 - Burning Hands
SCRL69 - Charm Person
SCRL70 - Color Spray
SCRL71 - Blindness
SCRL72 - Friends
SCRL73 - Protection from Petrification
SCRL75 - Identify
SCRL76 - Infravision
SCRL77 - Magic Missile
SCRL78 - Protection from Evil
SCRL79 - Shield
SCRL80 - Shocking Grasp
SCRL81 - Sleep
SCRL82 - Chill Touch
SCRL83 - Chromatic Orb
SCRL84 - Larloch's Minor Drain
SCRL85 - Blur
SCRL86 - Detect Evil
SCRL87 - Detect Invisibility
SCRL89 - Horror
SCRL90 - Invisibility
SCRL91 - Knock
SCRL92 - Know Alignment
SCRL93 - Luck
SCRL94 - Resist Fear
SCRL95 - Melf's Acid Arrow
SCRL96 - Mirror Image
SCRL97 - Stinking Cloud
SCRL98 - Strength
SCRL99 - Web

SHLD01 - Small Shield
SHLD02 - Small Shield +1
SHLD03 - Medium Shield
SHLD04 - Medium Shield +1
SHLD05 - Large Shield
SHLD06 - Large Shield +1
SHLD07 - Large Shield +1, +4 vs Missiles
SHLD08 - Buckler
SHLD09 - Buckler
SHLD10 - Buckler
SHLD11 - Small Shield
SHLD12 - Small Shield
SHLD13 - Medium Shield
SHLD14 - Medium Shield
SHLD15 - Large Shield
SHLD16 - Large Shield
SHLD18 = Large Shield

SLNG01 - Sling
SLNG02 - Sling +1

SPER01 - Spear
SPER02 - Spear +1
SPER03 - Spear +3, Backbiter
SPER04 = Spear +3, Backbiter

STAF01 - Quarterstaff
STAF02 - Quarterstaff +1
STAF03, STAF04 = Quarterstaff

SW1H01 - Bastard Sword
SW1H02 - Bastard Sword +1
SW1H03 - Bastard Sword +1, Shapeshifters
SW1H04 - Long Sword
SW1H05 - Long Sword +1
SW1H06 - Long Sword +2
SW1H07 - Short Sword
SW1H08 - Short Sword +1
SW1H09 - Short Sword +2
SW1H10 - Short Sword of Backstabbing
SW1H11 = Flaming Sword (no THAC0 bonus, no information in description)
SW1H12 = Hull's Long Sword
SW1H13 - Moonblade
SW1H14 = Short Sword +1
SW1H15 - Scimitar +3, Frostbrand
SW1H16 = Scimitar, +5, Defender (Drizzt's sword, only usable by good alignment)
SW1H17 = Perdue's Short Sword

SW2H01 - Two Handed Sword
SW2H02 - Two Handed Sword +1
SW2H03 - Two Handed Sword, Berserking
SW2H05 = Two-handed Sword
SW2H06 - Spider's Bane

WAND02 - Wand of Fear
WAND03 - Wand of Magic Missiles
WAND04 - Wand of Paralyzation
WAND05 - Wand of Fire
WAND06 - Wand of Frost
WAND07 - Wand of Lightning
WAND08 - Wand of Sleep
WAND09 - Wand of Polymorphing
WAND10 - Wand of Monster Summoning
WAND11 - Wand of the Heavens

XBOW01 - Heavy Crossbow
XBOW02 - Heavy Crossbow +1
XBOW03 - Heavy Crossbow of Accuracy
XBOW04 - Light Crossbow
XBOW05 - Light Crossbow +1
XBOW06 - Light Crossbow of Speed