Press "~" or "Ctrl+C" to bring up the console, then type the code.

Effect	Code
Disable AI processing	aitoggle
Disable build restrictions	buildall
Disable fog of war, get full intel on enemy units	nofog
Disable research restrictions	researchall
Enable cheats (needed before most of the commands below)	joshua
Full control over enemy units, plus most other cheats	god
Open AI character list	chars 2
Open AI construction screen	build 2
Open AI faction manager	facman 2
Open AI tech tree	tech 2
Prevent AI from attacking and avoid game over by score	fishbowl
Spawn highly skilled officer	newchar 20
Toggle FPS display (not a cheat)	fps
Unlimited Elite level crew	set faction.crew5 -1