you don't need yeast, but what you'll end up with is a tough crust, also....don't work the dough too much or it will get tougher....with yeast you have to let it rise for a while, but with baking powder (assuming it's double acting) you can let it sit for less, and let the heat do the work...
don't forget, if you let it sit, cover it with plastic wrap so you don't get a dry surface on the dough