Well, I suppose you could, but I don't really know how Vai does them.

I think he calls his two handed chords cluster chords, because the chord tonalities are close together. A chord with the notes C - G - Ab would be a cluster chord.

That tab I posted isn't for cluster chords, if that's what you were interested in. It's just to show two hand tapping to make some cool chords.

Peace out.

-Christoph