Pause during play, then enter the following codes:
L1, L2, L1, L2, Up, Right, Down, Left.
Up, Down, Left, Right, L1, L2, R2, R1.
R1, R2, R1, R2, Up, Down, Left, Right.
Up, Left, Down, Right, Up, Right,
Up, Down, Up, Down, R1, R1, L1, L1.
Left, Right, Right , Left, L1, R1, R1, L1.
Left, Left, Right, Right, R2, R2, L2, L2.
R1, R2, Right, Right, Left, Left, L2, L1.
Thanks to Revolution readers Minkus and Martin Brodeur!