Little Steven has played quite a bunch of time together with the band. I guess the most famous show they did was that Hard Rock Cafe Berlin(?) appearance when Jovi, Van Halen, Little Steven and Kingdom Come did a jam session. That must have been a hell of a show. Also, if you look up the youtube thread you'll find them performing This Ain't A Love Song together.

They have also jammed in the 80s, I am sure of that. Don't know when and what songs though...