Why do you need this? Sound Blaster 16 (PNP) driver works fine. Also, you can try both High Definition Audio and AC97 emulation with Uniaud, one of them should work, if I correctly remember.
Ah, I understood. You want sound support for OS/2 host. Unfortunately, sound is not working under host OS/2, yet. But OS/2 guest running on any other host, works with sound. Sound support is quite an effort for me, as I didn't worked with sound applications, yet. Need to learn a bit, how to work with sound hardware.
PS: The VBox development is paused a bit, because now I am working on fat32.ifs. It will be continued soon. There are some problems with financing, though. Last time, I was enhancing the shared folders IFS in the OS/2 guest additions. Will need to finish it first. Not sure yet, when I could work on sound support.