Hit left, square, up, triangle, right, circle, down, X at the cheat selection screen.

Hold right and press: sqaure,L1 (x3),sqaure,L1,triangle,X.

You want to be invinsible enter this cheat in the cheat menu (go to options then you will see cheat menu)

left, square, up, triangle, right, circle, down, x

full health
left,square,up,triangle,right,circle,
down,x

slow motion
right,square,up,triangle,right,square,up,triangle

invisibility
right,square,left,circle,right,square,left,circle

alien mode
up,triangle,up,triangle,up,triangle,up,triangle

lo gravity
up,triangle,down,x,up,square,down,x

God Mode:

Left,Square,Up,Triangle,Right,Circle,

Down,X,Start