That would disable the achievement, if you just enable the godmode, the game will automatic disable the achievement. And it would be very nice if CH make the Trainer for the orange box, and do the auto update just like L4D and L4D2.
You will need to put a request in for a trainer. As that one appears to be a user made one. Who is no longer here.
So go to www.cheathappens.com/requests.asp