He should have said, “Fire at will!”
That may have been a little over the top but I assume one in good condition would fetch a nice sum on ebay these days.
In December 1976 (while Gilmore was demanding to be executed), the cast of Saturday Night Live dressed in festive Christmas clothing and sang "Let's Kill Gary Gilmore for Christmas." Unfortunately, they didn't get their Christmas wish and had to wait over three more weeks.