Line an old cookie sheet with foil. Or use a disposable one.
Spray beer can holder with non-stick cooking spray.
Open your beer of choice, and drink about 1/3 of it. (you can dump it out, but that would be wasteful)
Place open can of beer in the holder, and place your chicken over the can.
Sprinkle the whole bird with Salt & Pepper
Stick the potato down in the neck.
Place bird on the cookie sheet and the cookie sheet on the grill and grill on medium heat for about 90 minutes, or until meat thermometer reaches 180 degrees. Checking occasionally to make sure it's not burning.
Cooking times can vary greatly based on the size of the bird.