It works!

A real pain to track down some current info on this old dog, since most of the suggestions are outdated. First off, ALSA provides OSS emulation these days, and it's already included in every distro I've gotten my hands on in the last year. And you need to use the OSS drivers here. Slackware also includes a very useful tool, alsaconf, that helped automate the setup, though I had to specify for alsaconf to "probe legacy..." and "all DMA/IRQ combinations", and "modify modules.conf" to have it actually dig deep enough for the right drivers, which are apparently

snd-cs4232
snd_mixer_oss, snd_pcm_oss, soundcore,...

Just in case, I chmod +x /etc/rc.d/rc.alsa to be sure the alsa configuration would automatically run at boot, and used more from the alsautils package: alsactl store to lock in the soundcard's setttings, alsamixer to adjust volume.

Well, after figuring all that out, it was nice to finally hear music on that old Omnibook 900. Sadly, the volume doesn't crank up high enough, but the sound is pretty clear. Also, not only doesn't the OS detect the need for the right drivers automatically, but it insists on loading alternate drivers that are admittedly described as fitting, but fail to work at all: nm256_audio, snd_nm256, ad1848. Not even blacklisting these drivers kept the operating system from loading them at boot!

So, the rating is rather ambivalent, but I would have to recommend ths product because the right drivers are still available in the kernel, though they take some digging to find and load correctly.