Each show has its own rules and specifics, so you are best to ask those in charge.
When I entered into two Fairs last year, and read the instructions, I was at a loss as to what to do ... and a simple phone call, helped to calm me fears. It turned out that so long as the size of the sleeve was met, most people simply pinned the sleeve in place with safety pins.
It was exciting ... as it was the first time I'd shown ... and the first time I'd seen my quilts hung!!!