i haven't listened to vulgar display of power in a while, but i think the lead part you're talking about is harmonised, at least two guitars. if you listen to the faster (and incredibly cleanly picked! ) solo later in the song, it's probably a similar tone to that, which should be easier to get, then add some kind of harmoniser effect.
he did use randall amps, i'd imagine on the pod the closest would be the rectifier or soldano models, or their insane one. and try using less distortion than you first imagine! we do tend do pile on the drive and then mess around with e.q. it works better the other way around
