you can use HTC TOUCH diamond GPS with installing TOMTOM gps application. you should download tomtom application, or download free google map for your HTC TOUCH phone.

How to use external GPS in HTC TOUCH diamond:
Launch the TomTom application, tap on the screen, and tap on Change Preferences, go to preferences screen 3 of 5, select Show GPS Status and select Configure. Select Other GPS NMEA and set the baud rate to 4800. Next, set COM port to COM4. Wait until it acquires a GPS signal and then tap done.

Tags: HTC TOUCH diamond gps, HTC TOUCH gps setup