Mastering on the PSP often requires a little help from cheat codes, whether you're trying to unlock your favorite characters or multiply your stud count to reach that 100% completion mark. How to Enter Cheats on PSP
Unlike some earlier LEGO games where you had to find a specific "classroom," entering cheats in LEGO Indiana Jones 2 is straightforward and can be done during active gameplay: the game at any time. Navigate to the "Extras" tab. Select "Enter Secret Code" . Input your 6-digit code using the on-screen letter columns. Essential Multiplier & Gameplay Cheats
Multipliers (x2, x4, etc.) can be active simultaneously, meaning you can achieve a massive x3840 stud multiplier if all are enabled at once.
Remember that you must finish a story level once before you can use your newly unlocked cheat characters in that specific stage. LEGO Indiana Jones 2: The Adventure Continues Cheats - IGN