Update: Under later versions of Parallels Desktop and VMware Fusion, the USB problems listed below shouldn’t be an issue.
Note: Some of the solutions listed below may have been superseded by later versions of the virtualization software.
Parallels Desktop for Mac
Parallels USB Drivers (web.mac.com/michaelsimpson) – Mac OS X USB drivers to assist Parallels Desktop for Mac when using the following USB GPS devices:
* Earthmate LT-20 with Street Atlas 2007 and 2006 (2006 didn’t update but every 5-30 seconds)
* Earthmate USB – with Street Atlas 2006
See this thread for more information.
It’s been suggested to install libusb-0.1.12 and emul-1.0.10 in Mac OS X to assist the pass-through on USB devices such as these.