Begin the game using the command line parameter +developer1 (ie. kingpin.exe +developer
1). Now start a game, and during play press ` to bring up the console. Now enter the
following codes:

god or immortal         God mode
give all                All weapons and items
give weapons            All weapons
give ammo               Full ammo
give cash #             Get # amount of cash
give health             Full health
give key(1-10)          Get key # 1-10  
noclip                  Toggles clipping