wacom(4x) is configured automatically via devd or HAL. However, if you
prefer to do so manually copy and edit the sample:

  $ cd %%PREFIX%%/etc/X11/xorg.conf.d/
  $ cp wacom.conf.sample wacom.conf

moused(8) may interfere with tablet input by attaching to fake /dev/ums*.
To prevent that add a usb_quirk(4) then detach and attach the tablet.
%%PREFIX%%/etc/rc.d/wacom is an example how preserve quirks across reboot.