http://msdn.microsoft.com/en-us/library/ff540196(v=VS.85).aspx --- See the WinUSB api, there is more to it than that.
Bottom line is, if you want to mess around with a device, you will need the implementation details for that device, for example, what commands to send to a device to get a response, etc.
USB ports carry both data and electricity ranging in miliamps do the wrong thing and you can trash your device.