Long marination in olive oil, wine or balsamic vinegar, apple juice is required. Antelope has no fat, so cook slowly and seal in juices. Sage is already built heavily into the meat, don't add more.
I've prepared it similar to venison... either marinate it and cook slowly as Tim says above or grill medium rare for the cutlets and steaks. If you make burger, add some pork fat. They do vary in flavor and quality so please report back.
I never hunted them but friends from MT back in college in Missoula used to turn them into tacos a lot. They said it was the best way to eat them because the seasoning covers the overwhelming sage taste .
Or they were college students that just wanted a reason to eat tacos with their excessive cerveza consumption. Either way, an option I suppose. I may or may not have eaten them. Frankly, I probably would not remember even if I had.