I'm running CRUX 2.1 (converted from devfs to udev) and I have fusd subsystem working using the following in /etc/udev/rules.d/fusd.rules:
SUBSYSTEM=="fusd", NAME="fusd/%k", GROUP="users"
It's basically a mix of the line from the oss2jack page, the posts above, and the format of the existing /etc/udev/rules.d/50-udev.rules on my system (note the "==" for the first entry on each line).
to my /etc/rc.local to load the fusd module at boot time, and commented out
because on my system sound-service-0-3 is an alias for the snd-pcm-oss module and according to the oss2jack installation you shouldn't have it loaded.
I then run:
jackd -d alsa &
as a regular user (note the "GROUP" is set to "users" above) which creates a /dev/dsp device. I can play quake3 whilst listening to mp3s now! I have noticed using oss2jack is that there are momentary pauses when accessing menus in firefox and things like that which might require some extra processing power and thus interrupt oss2jack a little. One thing I still have to get working is ventrilo or teamspeak. oss2jack was supposedly a solution to the game+voip problem with dodgy sound cards (mine's a intel8x0, otherwise known as an ac97). At the moment I can't hear any output from ventrilo (I can without fusd/jackd/oss2jack -- with the old oss/alsa pcm drivers, but not now). It's probably something simple in the settings of one of the above, so I'll keep trying.