Depending on which version of the show (actually, what "pit" instrumentation) they will use, you will need tpt, flugel and perhaps pic.
This will get you started with snippets of the tunes, however I suggest going to pick up the soundtrack (make sure it's the Broadway version, not the movie) and give it a listen. That is always extremely helpful.
http://www.mtishows.com/show_songs.asp?ID=000262
Have fun!