Your Songsling project seems really interesting but not fully understanding how it works. Are you generating a site+server and uploading it to the "linked" domains? Is "linking" asking for some kind of upload/write access to their host?
Thanks! It works through DNS — you point your domain’s nameservers to Songsling, then it manages all the other necessary records automatically behind the scenes. Basically it points the domain at the generated site. It’s still early, rough around the edges, but slowly getting there. The new audio engine that’s in the works is on a whole another level, focusing mostly on that at the moment.