Here's what I was able to find from several sources. Of course, the old rule applies: "Subject to change...."
May 4-6: Doug Chiang (Design Director for Lucasfilm Ltd.) and Kenny Baker (R2-D2)
May 11-13: Carrie Fisher (Princess Leia) and Peter Mayhew (Chewbacca)
May 18-20: Warwick Davis (Wicket the Ewok) and Jeremy Bulloch (Boba Fett)
May 25-27: David Prowse (Darth Vader) and Phil Brown (Uncle Owen)
Have fun!
Joe