Only New Ware is working on that at the moment. The trouble with the Gemini interior is that the shapes and such of the kit don't match the real thing without lots of work. You basically have to cut away eveything on the inside and start over.
Go here:
http://www.ninfinger.org/~sven/models/dwgemini/gemini_b.html
For a super article by Dave Weeks on the Gemini. It's the Airforce version of the Gemini but the techniques are the same. He's probably one of the best builders (non-commercial) I have ever know. Very meticulous. He designed the external detail set that Realspace Models sell.
John