Well, I think I found what I was looking for, but had no luck ultimately. WWise has a tool installed along side it called File Packager (it's buried in its install location). So I followed the youtube tutorial (from audio kinetic) to import my wavs into WWise, convert to wems, create a sound bank, then used File Packager to read the sound bank and create the pck. The I used Fluffy Quack's mod manger to inject the pck into the pack. Unfortunately, all this achieved was silencing the bgm.
Now I'm not sure if they really are wems in the pck since the RIFF headers in the pck don't match the RIFF header in the generate wems. So I wrote a program to replace the data portions of the audio in the pck with the audio from my wavs, but I still get silence. The RIFF headers in the pck do suggest the audio has 4 channels though, so I'm wondering if that's my problem. Anyway, still pretty stuck.
Can you upload a program you wrote?