Here are some other gentle things to try- gravity does the work to help shoulders drop.
http://neurotalk.psychcentral.com/album.php?albumid=422

Book - Conquering Carpal Tunnel Syndrome and Other Repetitive Strain Injuries- by Sharon Butler has very good stretches for all RSI /TOS with info on posture causes and corrections. She has detailed stretching ideas to gently coax the damaged tissues to release-not to force them. her website has many articles & a lot of information.
I found it very helpful.
http://www.selfcare4rsi.com/

Useful sticky thread - a lot of collected info over the years.
http://neurotalk.psychcentral.com/thread84.html