Unlike MSComm, this requires the use of API calls. Fortunatly Win98, Win2k have built in API functions to take advantage of USB. Unfortunatly, using them can be pretty deep, especially if your going to design your own hardware. This site, has plenty-o links and info on this. I highly recommend the USB book that this chick wrote as well! The book goes directly into designing hardware and writing VB code with respect to USB.

http://www.lvr.com/usb.htm

Hope this helps!
Phil