Hi: You can ask for a drive from vendor,just like Keithley http://www.keithley.com/main.jsp?action=keithleydownload&clickPath=Download+Center%5Esoftware+drivers&downloadType=download&itemType=software+drivers&role=Public+Download
Oliver, You can submit driver requests for these instruments at: http://zone.ni.com/idnet97.nsf/instrumentdriverrequest/ NI develops instrument drivers based on popularity and instrument availability.
Without an instrument driver, you can communicate with the instrument by sending it the appropriate commands using VISA. The Instrument I/O Assistanat in LabVIEW 7.0 or later can help simplify instrument communication.