I could not find Junebug firmware to download on Bill's site but the Inchworm programmer firmware is available on the Inchworm product page.
Bill, by the way, is a long-time member of this site and is one of the top respected posters helping people out here. Perhaps if you ask him nicely he'll send you the firmware. However, I suspect that he charges money for it and since he makes money selling his Junebug kit I don't know how willing he'd be to just send the firmware to someone for free. I wouldn't. Maybe Bill is nicer than me though.
Torben