In-game just press '`' (tilde key) to bring down the console and
enter one of this codes.
Use " 0" to toggle it off and " 1" to toggle it on.
Codes :
aiGodMode = Enemy God Mode
aiProtectProtectee = Protectee Godmode
god = God mode
aiDisableEars = Enemy AI cannot hear you
aiDisableEyes = Enemy AI cannot see you
noclip = Walk through walls