We do this quite frequently around here. In fact my neighbor brought over 2 of them yesterday, and they were falling off the bone tender!

I just use any combination of seasonings that strike my fancy at the time (my favorite blend is called Everglades Seasoning but it's fairly regional). Set the chicken on top of an open can of beer with the legs and wings hanging freely (in other words don't tuck the wings under like you would for baking it (you can also use cola, ginger ale, 7-Up, Dr. Pepper etc.) and place on grill (indirect heat is best) and cover with lid. It usually takes about an hour depending on how hot the grill is. but the easiest way to tell, other than a meat thermometer, is the wings will sort of rise up and look like they're waving "Hi I'm done!"