Default XDA II / i-mate as a wireless modem using GPRS

This problem was so complicated in the XDA/Qtek. They said it is straight forward for the XDA II/i-mate.
I tried first using the i-mate as a modem via the bluetooth connection, after plugging a bluetooth dongle (USB to Bluetooth) to my Desktop PC.
It worked perfectly, with no complications at all. And it's fast.
But up to now, I didn't succeed in using the infrared connection nor the USB connection. I tried to install the modem in USBMDM.inf that comes with the companion CD: nothing (no listed modems). I downloaded and installed the IrCOMM2k for the infrared port, but then again, no modems (unless I go back to the old standard 9600!)
Any help or clue ?