Dedicated pointing device for a Xephyr instance

[schultz at ime.usp.br]

Hi,

I have a Xorg server (x11-servers/xorg-server) running receiving
input from a synaptics touchpad at /dev/psm0. I would like to run
a Xephyr (x11-servers/xephyr) instance in this server that would
take input from a different, dedicated pointing device, in this
case a USB mouse at /dev/ums0.

The Xephyr help mentions a -mouse option. I have searched a lot on
the internet about this and even tried to read the relevant part
of Xephyr's source code. While I could not understand the overall
structure of that code, I noticed no relevant KdPointerDriver
structure.

It also seems that is possible on Linux with a evdev driver. Is it
also possible on FreeBSD?