Enable Cheat Mode:
     Pause  game  play, then hold L + R and press B, B, Left, Y, B, A.
The following codes can now be enabled.

Commit Suicide:
     Enable Cheat Mode then press A, Y, B, Right, Y, B.

Hide HUD:
     Enable Cheat Mode then press B, Down, B, Up, Y, B.

Kill Enemy:
     Enable  Cheat  Mode  then press Down, White, L, Up, X. The person
you have to hunt down in various missions will be killed.

Pickup OSS Document:
     Enable Cheat Mode then press Up, A, Black, R, Up, X.

Disable Shellshock:
     Enable Cheat mode, then press White, R, White, L, Y, Y.