How custom is it?

I assume(hope?) it is usb device class HID(or whatever the equivalent is for blootooth devices), this is well understood and there will be SDL/independent drivers for it in a day.

On the one hand Microsoft's Xinput is sort of nice for standard interoperability. On the other it is sort of a crippled specification, woefully inadequate for anything other than a xbox controller, their earlier direct input driver spec(xinput is a shim on top of this) was more capable. but I still don't think it can specify a touchpad.