Edit the file "autoexec.cfg" in the "cfg" folder of the game and add "wirbelwind" (without quotes) to the end. You can now use the ` key to open the console. Enter the codes below, 1 to turn on the code and 0 to turn it off.
Code - Effect
godmode 1 - God Mode for Squad
game_noai 1 - Disable AI
i_am_an_alien 1 - Enable Transparency (after save load)
getitem # - Get Item Number #
setxplevel # - Set All Squad Members to # Level
cheat_showall 1 - Show All Enemies