Gary,
I would suggest one of two options: Either include the VISA installation with your distribution, or don't use VISA. You can automate the VISA installation, but I suspect this may not work for you.
I would suggest then that you return to the old serial port methods. They are fairly easy to use. They are a bit hard to find though. Dig around, you should be able to find them (National Instruments/LabVIEW 6/vi.lib/utility/sersup.llb ?)
Good luck