One movement in yoga is just what quiltswithdogs said - open and bend your hand back - first do each finger (gently but firmly), then do whole hand. (do both hands) The idea is to stretch the muscles in the opposite direction from what they are used to. I'm not sure I like the idea of flapping the hands hard - I think it's too stressful - but that's just my opinion.
Put both hands flat on the wall at arms length and press into the wall. (again - the idea is to stretch the muscles in the opposite direction).
Put your hands in front of you in a prayer position - then put finger to finger and press into each other.
When you sit at the table, put your forearms flat on the table, then lift only your hands and raise them back as far as they can go - feel the stretch.
I will go through my yoga books and photocopy poses that I think might help and I'll send them to you. They're not only good for your CTS, but for your back, legs, arms. In the meantime - do the above several times a day. I do a lot of knitting/crocheting and wear a glove. It's fingerless and kind of stretchy so it fits snugly - idea being to keep the wrist warm and give slight support while still being able to do needlework. I forget where I got them, but maybe Clothilde or a needlework place such as Herschnerrs or Annie's Attic.
I don't blame you for not wanting surgery. I've heard some that went well and some that didn't. I'll avoid it at all costs myself.