While playing, press R2, Triangle, R2, Triangle, Circle, X , Square.
Then use the following codes while playing:

Invincibility R2, Triangle, R2, Left, Right, R1
Infinite lives R2, Triangle, R2, Left, Right, X
Larger enemies R2, Triangle, R2, Left, Right, Up
Smaller enemies R2, Triangle, R2, Left, Right, Down
Full health R2, Triangle, R2, Left, Right, Circle
Full Chi R2, Triangle, R2, Left, Right, Square
Stealth mode R2, Triangle, R2, Left, Right, R2
All Kung Fu styles R2, Triangle, R2, Left, Right, Triangle
Enemies gush blood R2, Triangle, R2, Right, Left, Right