It took me quite a while to get all this information together and working. Instead of enduring the search over again, I am writing it down for myself and any others that may find it useful.
1) Visit Ryan Florence’s site for the bulk of the info.
2) When you add the web-server’s repository, and this is specifically for MediaTemple GridServer users, the SSH url should be:
ssh://serveradmin%mt-example.com@mt-example.com/home/#####/domains/mt-example.com/html/
where ##### is the GridServer cluster you are hosted on.