Plug controllers into both PlayStation ports before you boot the game. Hold down Start on controller two (the right one) while the game loads. Press L1, R1, R2, L1, Select, and Start at the main menu or while gameplay is paused to enable the cheat mode. The following cheats may now be entered during gameplay:

Cheat: Result *
Press Select on controller two: skip level
Press Triangle on controller two: God mode
Press Circle on controller two: infinite power
Press X on controller two: gain all items