Well technically nothing holds the drum cover on.
You are suposed to be able to just pull it off after you take off the wheel.
However there is a slot behind the drum where you can fit a couple of screw drivers. Put one in there and wedge up the spring loaded ratchet and use another to turn the star gear up.
I got this from my Haynes Manual, which you might want to drop 30 bux on by the way.
This should help if the shoes are what's holding it on because it will manually retract them. That being said I couldn't get one of my drums off using that method.
One came off no problem and the other will not come off.
I just wanted to clean them but someday I will have to face this problem when my shoes finially wear down so if anyone has any other suggestions, post them up.