Holy smokes this was a frustrating one to figure out but FINALLY I have it done. When I updated my Mac systems to Snow Leopard, my T-Mobile Web’n'Walk Stick would not work. It crashed my systems every time. There is finally a LEGITIMATE fix for it and not even anything fancy to be done. I may be that you stick is really an OPTION brand stick that has been rebranded to t-mobile.
GO TO: http://www.option.com/en/support/software-download/
Enter your serial number or IMEI number and then you will be redirected to the Globtrotter drivers for Snow Leopard. I have just installed and tested both applications and they work perfectly. If you have any trouble or complications, then contact me. GOOD LUCK.