Yah i heard you can turn off VAC on your own server. If your trying it tell me how you did it and if you got the achievements For survival, like all gold and stuff like that!! Your a pioneer for trying this out!
UPDATE:
It has been a few weeks since my last gold medal on my local server, and I just got another medal today. I haven't even tried to turn VAC off of my local server because I don't think it's needed. Just put -insecure in the command line parameter for safety.
As long as you do this on a local server (friends-only server), just for survival, or go to single-player and do off-line campaign, I think the trainer won't cause VAC to flag your Steam account for cheating.
Just remember: Don't play with this online and don't play with other online friends.