When paused press Up, Down, Right, Left, Square x 3.

At the item selection screen hold L2 and R2 while pressing:
Square x 3, Up, Left, Down, Right.

At the item selection screen hold L1 and R1 while pressing:
Up, Square x 2, Left, Square x 2, Down, Square x 2, Right, Square x 2.

At title screen press:
L1, R2, L2, R1, Right, Left, L3, R3.
(Press down left and right analog sticks for L3 and R3)

At the mission select screen press:
L1, R1, L2, R2, Right, Square, L3, R3.

As the mission select screen press:
R3, L3, R2, L2, R1, L1.

At title screen press:
L1, Up, R1, Down, L2, Right, R2, Left.

At start screen press:
Up, Down, Right, Left, X x 3.