@hamsterjam (and eltheos): I haven't looked at this extension for TC but in other distros you start and stop from /etc/init.d. So as root or via sudo:
/etc/init.d/mpd stop
Or whatever the path to ...init.d/mpd in this case. You can stop, start, restart, etc., based on that script so that it behaves as intended. Dittos for other daemons (cupsd, httpd, sshd, hald, etc.; some of these have more options for modifying behavior).
I just looked and saw this extension still has man pages, documentation, etc., included with it so you should be able to read all the setup information online when you load the extension:
usr/local/bin/mpd
usr/local/share/doc/mpd/AUTHORS
usr/local/share/doc/mpd/COPYING
usr/local/share/doc/mpd/NEWS
usr/local/share/doc/mpd/README
usr/local/share/doc/mpd/UPGRADING
usr/local/share/doc/mpd/mpdconf.example
usr/local/share/man/man1/mpd.1
usr/local/share/man/man5/mpd.conf.5
usr/local/tce.installed/mpd
Quickly, though, your mpd.conf (whether you set it up in ~/ or in /etc or wherever) includes which user is running the daemon (line with: user "username"; default is: user "mpd"). The recommendation is to set up a separate user mpd to run the service but you could use tc. If you have that set that in your mpd.conf (and that's persistent) and mpd starts after alsa, you shouldn't have any issues with it running. I just restarted mine (Debian Lenny) after changing user from mpd to my-login and now I own it.
Edit: If you have a persistent mpd.conf set up for user "tc" and mpd starts as any other user, you should only need to issue "/etc/init.d/mpd restart" after it's already loaded to change it to user tc. You could add that to /opt/bootlocal.sh and it should be taken care of by the time you'd do anything with it.