Unlimited lives:
Hold X + Circle + Square + Right at the title screen. Start the game. Hold L1 + R1 when playing as Milo for unlimited lives. Milo will say "Great" to confirm correct code entry

Action Code 

Infinite Health
800967620064   800967680064 

Infinite Lives
800967600063 

Unlock All Levels
Must have a previously saved game to load.
80098f3cffff   80098f3effff   

Have All Green Crystals
When used with "Unlock Levels" code, also unlocks "Concept Art" and "Model Viewer" under the "Features" menu.
8009676a0001   80098f40ffff 

Lots Of White Crystals
8009676a00ff