Guitargeek.com has some info on Jason's live rig during 2001 or so here:
http://guitargeek.com/rigview/546/. It says he used a Jaguar, which seems unusual as he's more know for playing a Jazzmaster. Whoever reported the information may have been confused. I feel like I've seen at least one picture of Jason playing a Jaguar though.
He's also see playing a telecaster at some of the shows from later years, and there's a gear page on his recording site.
http://www.jasonmartinrecording.com/gear.html