I know exactly the part your talking about. As a huge Satch fan myself, not only do I have the Live in SF but the G3 video as well (w/Eric Johnson and Vai). They play that tune on the vid so you can almost see what he is doing there. That part is just a bunch of fast pick slides on the A and D strings (at least that's how I play it - sounds pretty close) that go along with the kick drum and Stu popping the A string. That's just before it goes into the main riff and melody.

The pick slide starts off real fast and slows down towards the end of slide. It's all about technique so you gotta kinda feel the way Joe does when he plays. But do it your way. Not only will you feel more comfortable with it, it'll be you playing -- not Joe.

Later Man

JAM