sort of off topic, but not that much. at ultimarc's site, they say that the trackball they offer is fitted to work with te optipac. can this work with oscars usb mouse interface, or must i buy a tb from wicothesource? and if i want the interface with 2 buttons, i only need 1 (interface) , right? asking b/c it says spineer interface and a trackball has double the axis of a spinner.