Start the game with the parameters 
"-drake -strega -amitab -fuzzyhead -mice". 

In the game itself (when your actually driving) use 
the following keys for the described cheats: 

Code    Result
--------------
F7    - God Mode Toggle On/Off
F8    - Invisible Toggle On/Off
F10   - Mission Complete AUTO
F11   - Mission Complete MANUAL
F12   - Mission Failed