I've successfully implemented DShaper into m0n0wall.
You can view an image at http://paxetman.com/dshaper/m0n0-dshaper.gif
More info available here:
Please note, the image shows several fields as being mandatory, however,
only MaxBandwidth will be needed.
If you would like the image for testing purposes, please email
dshaper at paxetman dot com
It should be available at http://paxetman.com/dshaper shortly(Monday