Hit the enter key and type:
autowin -- Instant Win
dolemite -- Invincible Soldiers
paul haney sees all -- Show Enemy Troops
toggle bottombar -- Switch Bottom Display
Hit the ENTER key and type set_campaign.
To select which campaign, add one of the following after the above code:
Go into Multiplayer and host a new game. At the game settings, set unlimited ammo. Start the multiplayer game, then quit. Start a new game or load an old game.