The best method i've found SO FAR is to attach the M00_Base_Defense script to a tank that already has a path assigned to it. Sounds strange, but the tank will attack anyone it comes across. But, however, once it has spotted and attacked someone, it wont move anymore .

I "REALLY" wish greg could release the Scripts source, or at least an editor, soon. I could make a copy of that script so it takes mobile vehicles into account.