I used a wooden paint stirrer stick on my XJ, just slid it up to each Christmas tree clip, rotated and popped. I have no idea if its the same on a YJ though.
On my TJ I used two screw drivers, but the paint stirrer sounds like a good idea if you can get it inbetween the panel and door. Dont worry about breaking anything. I had no problems getting it on and off and if you do happen to break one of the clips, I imagine you can get them for cheap somewhere.