I have a Toshiba DLP 50HM66 and I can't find a way to access the Service Menu with the remote. I use a PS3, and whenever I watch my encoded home movies on it I get overscan on all sides. I'm guessing that some option in the service menu would help alleviate this?

Have you looked for a thread for your TV?
http://www.avsforum.com/avs-vb/showthread.php?t=663974

For SM access (at your own risk) try here;
http://www.fixyourowntv.com/servicemenu.php

but a far better source is here;
http://www.riddledtv.com/forums/tv-service-menu-codes-f13.html