Activate cheat mode in the options menu: {XBox}
Aliens Versus Predator: Extinction: Cheat Codes [Xbox, PS2] Free Download
While paused, press L, L, R, L, R, R, L, R, L, L, R
Activating Code Mode: {PS2}
During the game, press pause and enter:
[R1] (x2), [L1], [R1], [L1] (x2), [R1], [L1],
[R1] (x2), [L1], [R1], [L1] (x2), [R1], [L1].