I've taken a closer look at the SDK, and so far it's easy to import the C functions into C#. I've done the whole Alc.h header file and wrote a little test app to query devices/strings/ints/etc. and it seems to work fine with the "SB Live! Wave Device".
My question is now: Is there anyone working on OpenTK.OpenAL already? It was just an exercise to see if I can do it, and if this is already WIP by someone more experienced with importing, i'll just put it into the archive and forget about it.
If there hasn't been any work done for this, I'd continue porting FreeAlut.h and Al.h to C# too, but the Al portion is rather large and I don't want to do this if it's already addressed by someone else. It's not so much the import that's the issue, it's the quantity of documentation for the functions.