I find that icing the ear works well. I place an ice cube on the outside of the ear for a couple minutes, and use a RabbiTatt. The rabbit usually doesn't even notice what I'm doing, except for the hum in their ear... I recently got a 5 point needle and tip, and find that it works better than the 3 point. You don't have to go over it so many times to make a good line.
Yeah, practice on a banana. A couple of banana's! Get a feel for the electric tattoo pen, before going near the rabbit.
You can try contacting other breeders in the area to see if they will have their pen with them at the show. The pen can literally be used right before they go on the table. (I did 16 rabbits last weekend at the show... 3 of them right before they were shown!)