There is regular jam sessions at The Palapa Bar, Fido's, sometimes BC's. Get the 2 local newsparpers whern you get there and see who's where. Dennis Wolfe hosts open mics & Barefoot Skinny as well (if he is on the island at that time). Also check out Mata Grande Hotel
http://www.matagrandestudios.com/on the N side (used to be Sundiver, just ask anyone for directions) Now owned by a musician and has a recording studio, etc. They often have jams as well. You'll have fun!