There's lots of anti-carpal tunnel devices, particularly ergonomic keyboards, but my impression is that pointing devices are very hard to pry from the hand (and the carpals). It seems to me like your best bet might be to relieve the need for clicking rather than pointing. Adding a foot pedal to your PC set up might be your best move. They can get pretty expensive. The Fragpedal is mostly aimed at the gaming crowd, but has a nice feel, and might be your cheapest bet -- a four-button set costs $79. Here's a link to the product page: http://gamingmouse.com/weapon.php?pid=175
I'd recommend assigning a button to left click, right click, and maybe double click. It also supports any other key stroke, as well as advanced nacros (key sequences, combinations, conditional statements, counts, etc., so it can easily free you from having to ever click with your mouse hand, and might clear up some room on the keyboard also.
I'd be interested in hearing how you end up resolving your situation!
The OrbiTouch looks like it's only for people who have serious hand disabilities, since it requires a complete re-learning of how to input key commands, and you'll likely never be able to reach higher typing speeds. Although it's an interesting idea -- I've seen suggestions that similar chording systems for game console controllers. (It's also $400)
Sorry for the old-thread revival, but I think I might be able to help. A few months ago, I too started getting pain when holding my mouse, I don't know if its related to carpel-tunnel, but the pain was in my wrist and on the outer rim of my palm, like near the pinky finger, not the inside part. I don't know what it was, but I went ahead and got another mouse and it stopped...just like that, it simply stopped. Turns out I was using a mouse too small and causing my hand to cramp. So try changing mice.
The second thing that helps alot, is a wrist compressor (its probably called somethign else). Two handles and you compress them with your grip.
I don't know if it will help, but I recommend trying them, it helped me a lot