To enter the passcodes, simply click on Settings from the game's console, then click on General. Type in the passcodes into the blank area labeled "Enter Passcode Here". To delete a passcode, i.e, the Chicken Passcode (hate being a chicken?), simply click on the passcode, and press Shift-Del.

ACE = Increase Level Difficulty
NEUC = Destroy all imperial ships on radar
HIKEN = Hidden secondary weapons
LOKJOT = Land and repair
CREDITS = View credits
CHICKEN = Control AT-ST
IGIVEUP = Infinite Lives
FARMBOY = Fly Millennium Falcom
GUNDARK = Changes force feedback control for joystick
MAESTRO = Let's you listen to all the sound themes. Select "Concert Hall" from the High Scores menu to activate
IAMDOLLY = Infinite lives
TOUGHGUY = All power-ups
DIRECTOR = Let's you view all the cutscenes. Select "At the Movies" from the High Scores menu to view the cutscenes
NUMBERTWO = Infinite secondary weapons
USEDAFORCE = Unknown
LEIAWRKOUT = Activate joystick force feedback feature