I didn't get the impression they've been trained. I think they function as a twisted Aiel society: they train each other, and given the rules in place, it seems to me they must be trained during raids in the Blight, far from the town itself (where it appears they're forbidden to channel or there's a mechanism in place to prevent them touching saidin. We know apparently not all of them have been turned either, it sounds like some were raised there.

My intuition is that they're forbidden or prevented from touching saidin and aren't insane from the Taint. Rather it's the True Power they use, and the DO is not letting them use it in the Town itself... but Moridin of course is allowed.
As for being insane I'm not so sure. The taint is very debilitating... few would last very long if they used saidin without protection, which they may not have/use because they simply don't use saidin...

As for their behaviour and totally wild side, I'm not sure it's insanity so much having been turned... and being Aiel in the first place. RJ gave the impression such people become utterly and completely evil, as if they had been immersed completely in the essence of the DO by the 13x13 ritual. Aiel without ji'e'toh to humanize and civilize them would be pretty frigthening....

I also find it pretty interesting that at the end of TOM Fain seemed to be nearing that town... a town where a lot of people, like him, have been forced by the Shadow to do things against their will...