I had tendinitis in both wrists as a college undergrad. Not a pleasant experience, to say the least, particularly when one computer lab in which I had to work had the keyboards security-chained to the desks, limiting the ability to get a comfortable work environment. The therapist gave me all kinds of exercises and stretches to do, custom-made braces to wear, ice and anti-inflamatory drugs, etc., but I didn't really heal until I took matters into my own hands, as it were.

1) I bought a Kinesis ergonomic keyboard. I was actually their first credit-card paying customer. I can talk at length about why I feel the Kinesis is superior to many of the Microsoft-style "natural" keyboards, but that's a topic for another day. At the time, it cost $700 (now $200-$300 depending on model). I was doing research for one of the CS professors, so I talked him into splitting the cost 50/50 with me. Since I was using a Sun workstation, which didn't take a PC keyboard, I also found an old 286 machine, on which I ran custom software to output the keyboard codes on a serial port, and then had custom software on the Sun to read the serial port and talk to the X server. (These days, all the world can deal with either PS/2 or USB, and adapters are cheap.) I generally typed with the keyboard in my lap to have it nice and low.

2) Once I started grad school, I had my own desk that was height adjustable. I had the keyboard height as low as was possible to get my legs underneath. I removed the arm rests from my chair. I also used the handicap-accessible bathroom's sinks (with high water faucets) to simulate hot/cold contrast water baths by flipping the controls from cold to hot and back. I was able to get most of my forearm under the water, all at the same time.

3) I realized that heat mattered a lot when I was typing. Going from long to short sleeves significantly increased my discomfort. I eventually solved the problem by talking a friend, who had offered to trade hand-made socks for a home-cooked dinner, into knitting "wrist tubes" for me (essentially socks without feet). I still wear these today when I type and when I drive. She and I learned later that knitting people, who also commonly suffer from repetitive strain injuries, commonly knit these sorts of things for themselves, calling them wristlets. (Unlike that link, my own wristlets don't go around the thumb, they're just four-inch tubes on my forearms.)

4) As I've had summer internships or other times that I've worked outside of the office, I've left a trail of $30 Kensington keyboard trays behind me. They're easy to (permanently) install in just about any desk. I prefer the models without any sort of wrist rest, since the Kinesis effectively has one built-in. The Kensington tray is wide enough to fit the mouse inside, so you don't have to reach too far for it.

Clearly, you understand that you need to improve your work environment. My recommendation is to do it on the cheap, on your own dime. A couple hundred dollars for a good keyboard and tray is noise in the grand scheme of things. Even if you have to buy yourself a good office chair, you can always take it home with you once they get off their duffs and buy good ones themselves. All of this is far cheaper than hiring a lawyer. Furthermore, if all of your co-workers see how you've modified your environement and like it, they may start doing likewise on their own or separately demand accomodations from the company.

Obviously, I'm not qualified to recommend whether you go ahead with the surgery or not. However, if you don't address your work environement, it's likely that you won't ever get back to normal, surgery or not.