The Agilent 8163, 8164 and 8166 uses the same driver and they come with the mainframe. If you didn't get the driver with the mainframe, call Agilent's T&M support and ask them to email it to you.
FYI, there is a bug in the LabVIEW driver that Agilent supplied.
I hope that helps. Regards,
Shan Pin Koh
Systems Engineer
Oakriver Technology