Using this Trainer:
Launch the trainer first, then launch the Game and then Press F1 at the Main Menu.
Listen for "Activated".
Press desired option key
Options in Promo:
Numpad 2: Unlimited Ammo
Options:
Numpad 1: Unlimited Health
Numpad 2: Unlimited Ammo
Notes:
Numpad 1: Unlimited Health - toggle this on and most things cannot kill you.
Numpad 2: Unlimited Ammo - toggle on and the gun has unlimited shots.