Welcome to the QB. Most quilt shows are put on by quilt guilds or quilting groups. Is this the show you are interested in?
http://quiltshownews.com/quilt-shows...new-york-2015/
If so, scroll way down and there is a reply by Deborah Richmond. I would contact her to see if they are looking for volunteers.
Here is another one in July
http://www.quiltingbythelake.com/visitor.html
Try contacting them.