I know that this isn't really a very common issue anymore, but the solution is quite simple, so I figured I'd put it here for archiving's sake.
Make sure that /proc/asound/card0/pcm0p/oss is writeable (if you trust your system enough, you can chmod to 777).
Create the following launcher:
echo "quake3.x86 0 0 direct" > /proc/asound/card0/pcm0p/oss && quake3
Granted, once the echo "quake3.x86...0p/oss
part is run once, it probably
doesn't need to be run again, but this way it runs each time before you launch the game just in case something somewhere else on the system changed something. The "&& quake3" part just runs the quake3 launcher once it's done w/ the first part.
Anwyay, this has always worked for me in the past, so I figured I'd pop in here and give you guys my little trick.
enjoy (and feel free to give suggestions on improving my method)