There are only a couple of tracks where Trent sings backup. Saul posted a very illuminating set of notes on all the tracks on his forum:
http://www.saulwilliams.com/cgi-bin/...c;f=2;t=002361
Keep in mind that Trent's production shows how well he fits in with producers like El-P, Prefuse 73, or even the Bomb Squad (PE!), who have been influenced by the industrial and noise scenes.