If your BBQ is big enough; close the lid. I had a smaller one before and closed the lid as much as possible propping it open with a rock. Basically let it cook while drinking the rest of the beer. About every 20 mins baste the chicken with the juices in the pie plates (I use a turkey baster); and turn the plate 1/4 turn when you do. It'll take about 1 1/4 - 1 1/2 hours to do but that really depends on your BBQ, cooking skills, etc.
I cannot take credit for this as I learned it from friends but was surprised it wasn't on here already. The kids love the recipe and it makes quite a tasty and fun BBQ meal. Enjoy.