Dayman - I've already run into that problem. I usually carry open on my hip right now or with a light jacket concealing the holster. It's definitely not the most advantageous place to carry. I had to remove the side rails from the chair to allow access to my gun. I'll definitely check out Wilson Tactical holsters. Hopefully they'll have something.
Avtomat - Shoulder rigs would work but for two problems. In the summer I'd have to wear a jacket (too hot) and the shoulder rig tends to bind under my arm, scraping my skin. I wouldn't consider an ankle holster. I would need to bend over to get to it and that could easily cause me to topple from my chair. Not a position one wants to be in when the bad guys are around.
Dave - My problem with mounting a holster to the chair is if I'm knocked out of it I lose my gun. Someone could walk up behind me and shove me out of the chair. So there I am on the ground with nothing to defend myself with.
Thanks for the responses, guys. It isn't an easy problem to figure out.