Hey Jim,
Your doing the right thing by searching the web and trying to find out all that you can about the condition and possible treatment. Most people wouldn't put much effort into it! Hopefully your local vet will be able to help you out. I think ALL vet clinics should have at least one doc that specializes in reptiles and hopefully that day will come, but until now, us reptile people have to do the best we can do!
My vet treats some reptiles, but only if the problem isn't too severe. Lat summer, I saw an Eastern box turtle get hit by a car so I brought it home, contacted my vet and set up an appointment for that afternoon. The turtle's plastron was pretty badly damaged, his hinge was completely smashed. Well, my vet took one look at him and said "all I can do for him is euthanize him, sorry! I can't repair a busted shell." Well, I wasn't happy with that answer! Despite what this turtle had went through, it had a strong will to live so I brought him back home. I had heard of people putting shells back together using fiberglass car repair kits, so I bought one and tried my hand at it. Well, it worked! His shell began to mend and I still have this guy. While he will never be able to be re-released into the wild, he seems pretty happy just being a pet and having a second chance.
Unfortunately, I don't think there's much you can do on your own for a prolapse, but hopefully you will find a vet with a better outlook on reptiles than my vet! It will more than likely have to be stitched back into place, poor turtle! Anyway, best of luck with your guy! Maybe he can be returned to normal before too much longer!