dry ice to remove hail dents

Has anyone here ever used dry ice to remove hail dents? If so, is there any trick to it other than apply the ice to the dents? For example, does it help if the vehicle is parked in hot sun when you do it? Can it harm the paint and thus needs to be in cloth or something when applied? In other words, I don't know the first thing about it, or if it even works. :-) TIA