I dont think recording techniques have much to do with sound. From what I've heard it sounds pretty straight-forward. He does seem to use effects alot though. Most of the weird shit is done by experimental stuff like taking his instrument cable out of his guitar and touching it to his strings or his bridge or something. That DJ scratch thing he did on "bulls on parade" was done by scraping an allen wrench against his strings while flicking his pickup selector switch back and forth. He had the volume on one off his pickups turned off, so when he switched between the two pickups it had an "on-off" effect. (Certainly anyone with a les paul style wiring setup on their guitar has experimented with that technique.)
Rage's guitarist gets alot of praise for his experimental methods, but to me alot of his stuff sounds like it was written by a guy with severe writers block. Who here hasn't tried alot of the things he does in his songs without ever hearing his work? I know I have out of boredom, but usually I just say, "okay that was fun, now im going to PLAY my guitar, instead of play WITH it.