Use these login names:
Flamdwyn Aiobhell       Unlimited ammo
Monty Barrymore         Unlimited ammo and invulnerability
Lyn Wins                Unlimited ammo, invulnerability, and enables 
                        other cheats

Other Cheats:
SHIFT-CTRL-ALT-TAB      Speed warp
ALT-V                   No fuel
SHIFT-V                 Refuel
ALT-T                   Overtorque toggle
CTRL-T                  Terrain-following toggle