That job is managed by Windows. As I have 2 identical USB joysticks, my device manager showed something like "Joystick XX#1" and "Joystick XX#2". And all games recognized both as #1 and #2.
In your case, It's you windows application which has to search for USB enumerated devices from the class that matches your device. If that app is your user interface VB6 application, there are many code samples in MSDN and many VB6 forums which play with this using API's. API's are to VB6 as Interrupts are to PicBasic Pro (of course API's are not hardware level, are just Windows guts level)

If still lost, or yet lazy to search, tell me, I could get it for you.