Hold down [Ctrl][Alt][Shift] while typing in one of the Cheats:

 superfunkicalifragisexy        Invulnerability
 iseenfireandiseenrain          Unlimited ammo
 ooohhhlllaaalllaaa             Heat tracking
 itsdabombinmybeautifulballoon  Sprout jumpjets
 tikruleslikethecomstarbaby     End mission successfully
 ontimeeverytime                Time compression key
 bubbleboy                      Bounding spheres
 crazysexycool                  Infinite jumpjets
 beholdmyglory                  Free eye mode
 antijolt                       Time expansion
 flashyflashy                   Auto-grouping
 walkthisway                    Leading reticle
 redjackandtikrules             Destroy targeted mech
 itsdabooomb                    Nuke targeted mech