Have you looked at VB6 TEMPer Gold USB HID Thermometer Class yet?
This may not address the issue of "following" a specific device when moved from one USB port to another, but you may find something useful there.
These devices are problematic though. They can spontaneously burst into sending data via the HID keyboard virtual device, which can wreak havoc when those keystrokes end up reaching the shell (Explorer Desktop).
Until the keyboard feature can be disabled on these devices they aren't ready for any kind of production use. I have never found any way to accomplish that.