Combine sugars, garlic powder, salt, pepper, paprika, mustard, cayenne, and sage in a small bowl. Coat chicken with olive oil, then rub 2 teaspoons of the spices over the chicken and season the bird's insides with the rest.
Pop open the can of beer. Pour about 1/4 cup of beer into another container, then use a screwdriver or bottle opener to poke a second hole in the top of the can. Place the can on the grill in the middle. You're going to want to cook the chicken over indirect heat.
Carefully position the chicken's cavity end on top of the beer can. It'll look like the bird is sitting on the beer. Close the grill. Let the bird cook for about 1 to 1/2 hours, until the thigh temperature reads 180 degrees F and the breast temperature reaches 165 degrees F.
Remove from grill, and don't forget to take the beer can out (and throw it away) before eating.