This would be a little hard to do, but try setting up an HWID, and PM each MPGH member their own. Whenever someone without one tries to use the program, have it open up tons of MPGH tabs. That'd be pretty funny. This is what the guy who made Krolek (CS:S bhop hack) did, minus the pop-ups.
Unless you have too many people using it. In that case, just blast it with MPGH ads.
Then again, they wouldn't care. At all.