Stand on whatever corner of the boat is downwind if you are turtle. She'll come up and start to catch the wind. I've righted them from bow or stern as long as your weight is downwind (and your mast doesn't leak).

As far as righting, no problem with your weight! Just try to orient the bows into the wind by standing on the bow of the catamaran on it's side (this causes the bow to drag in the water and swing the boat around). It won't want to stay in this position after you leave the bow so you should already have your righting line ready to grab over the windward hull in the middle of the boat.