I managed to Get Garmin to Work on my Sprint Q9C. However, the Com1 hack didn't exactly work because I believe COM 1 is used by the bluetooth. So, instead of COM1, I used Com2 and it work perfectly. So, follow the instructions for the COM1 hack but use COM2 instead and the associated settings instead. Also I am usin using Garmin XT 4.20.40w version.