I've never shown but this worked for me when I was documenting the weekly changes in one batch of my chickens and had to get them to stand still for pictures and weighing.
First make a chicken friendly place to practice. If there are a lot of distraction and stuff it may get nervous.
Second place chicken on stand and give a treat. Wait and then give it again. Start raising your hands towards her/him. If it jumps off, put it back and comfort it with a treat. Keep practicing different stuff (like walking away then back again).
Third add the distractions
Fourth, get someone to help you and put on a "practice" show. Set your chicken up, treat, walk back, let the other person come up, if need be let them give a treat so the chicken will think everyone will give it a treat.
Hope it helps
This sounds excellent. I have done something similar with my modern games for show. Chickens are very trainable and although they do not act this way in the barnyard I do believe they enjoy being trained and interacting with a person they trust. I believe they are a lot smarter than many people give them credit for.