well for embedded systems is not quite handy to just buy something and fingers-crossed it will work...
first of all it would be handy to check if the usb soundcard even works on a modern linux (ubuntu, opensuse etc.)
if that's the case it MIGHT be possible to compile a kernel driver and load it up...
also try to swich on waveserver in the webadmin (system setup > services).
basicly it tells you the stuff to do right here: http://home.in.tum.de/~pustka/WL-500...soundcard.html
so there might be a working driver out yet, unfortunately for an old oleg version