you could put put something in init.d along the lines of sudo -u <tremuser> /path/to/tremded.x86 +set dedicated 2 +exec server.cfg &
(i'm aware that there is probably a better way to do this than sudo, i'm just too lazy to find it) and symlink to it from rc.whatever. if you really want to know what they do, just grab the .deb, extract the contents (it's an ar archive)), then extract the tarball (i forget the name, it's the one that isn't control.tgz), the files you are interested in are etc/init.d/tremulous-server and etc/default/tremulous-server. i would have done all of that myself, but i don't feel like rebooting right now.