What we are going to do is a basic variant of a process generally known as reverse engineering. You start examining the device with common tools (USB is quite descriptive itself). Then you capture the data that the device exchanges with its existing (Windows) driver, and try to guess what it means. This is the toughest part, and you’ll need some experience and a bit of luck to reverse engineer a non-trivial protocol.
Bucktown Bell
Cut to the chase.
