Hello. With that command line, I'd say you need to have the UPS
attach as a uhid device rather than as a ugen device.
What happens if you boot -c, disable the ugen driver and let it boot with
your UPS plugged in? Do you then get something like:
uhid0 at ohci0 port 3
rather than
ugen0 at ohci0 port 3
If you do, then this programmight attach to the UPS and make it work.
If that doesn't work, then you may need to add the UPS vendor ID and
product IDs to the match routines of the uhid(4) driver specifically.
-thanks
-Brian