For the benefit of everyone else trying to get USB debugging working, this is
what I did:
1. Order the "Hi-Speed USB 2.0 Host-to-Host Debug Device" from
http://www.semiconductorstore.com
2. Plug both USB connectors into the host PC
3. Start WinDbg in elevated mode (run as admin)
4. Start kernel debug in USB mode, it should install drivers necessary
5. Unplug one USB cable and plug it into the target PC
6. In host PC's Device Manager, locate the "Ajays USB 2.0 Debug Cable", and
provide the missing driver for it from [WDK dir]\Debuggers
7. Locate USB "Port 1" on target PC using USBVIEW from the WDK
8. Plug the USB cable into this port
9. Configure target PC for USB debug, using same targetname as in 4) above
10. Reboot the target PC
/ Hannes.