I can confirm this works, and i'm so pleased I don't h ave to play through campaign again on PC + legit 360

source

Cheat mode
At the main menu, use the Right Analog-stick to look down at your hand and see you are locked up. Repeatedly press L2 + R2 to escape from the chair (unlocks the "Just Ask Me Nicely" secret trophy). After breaking free, move around to the area behind your chair to find an old computer terminal you can use. Type one of the following codes to access early unlockables and hidden features in the game. Note: You can also plug a USB keyboard into your PlayStation 3 to enter the codes and play the Zork text-based adventure game.

Mission select, "Five" Zombies mode map, Dead Ops Arcade game, Zork game
Enter "3arc Unlock" as a code to unlock the "Five" Zombies mode map, Dead Ops Arcade game, Zork text-based adventure game, and all missions.

All Intel
Enter "3arc Intel" as a code to unlock all Intel. Note: Enabling this code will prevent you from getting the "Closer Analysis" trophy.

Dead Ops Arcade game
Enter "DOA" as a code to unlock the Dead Ops Arcade game, which is a zombie killing mini-game similar to Smash TV. Use the Left Analog-stick to move and the Right Analog-stick to shoot. Note: Play the Dead Ops Arcade game to get the "Insert Coin" trophy.

Zork game
Enter "ZORK" as a code to unlock the Zork text-based adventure game. Note: Play the Zork game to get the "Eaten By A Grue" trophy.

Display all commands
Enter "help" as a code to display a list of system commands in the terminal and Pentagon user e-mail access.