During gameplay hold L1 and R1 and press Square, Circle, Triangle X, X to access the 'Code Entry' screen. Then enter the following codes to enable the effect you desire (when these codes have been enabled you will not be able to 'Save' your progress).
Unlock Health Restore:
Release R1 and L1, Hold R1 and L1 down again and enter Triangle, Square, Square, Triangle, X, Circle.
Unlock Infinite Ammo:
Release R1 and L1, Hold R1 and L1 down again and enter Circle, Circle, Triangle, Square, X, Triangle.
Added by: Sanzano Jan 8th 2008, ID#387