Be careful though. Butter contains water, shortening does not. Not sure how this might affect your recipe. You may need to reduce the liquid in the batter to make up for that which butter adds. Some recipes can handle the switch without modifying the liquid, some can't. Happy experimenting.
I would use Alpine shortening. It has a much cleaner and lighter finish than regular cooking shortening like Crisco. It also doesn't leave that nasty coating on your tongue! I get mine from a local cake supply shop.