OK, are you installing the drivers manually or trying to use the application load that comes with it?
Try simply installing the drivers and then create a Dial up Network Connection (DUN) for the modem (yes this works even for mobile broadband cards, your ISP can provide the settings)
I have seen a number of times where the software supplied by the ISP with the drivers will fail to install, in fact I posted a MDAC update for this issue on the website. This was so solve a problem with a local mobile card.
Unfortunatly I have not played with your specific device,
Cheers,
-TT