Thanks for all your advice and help. I used the methods you guys helped me with and had some observations in the aftermath:
1. 2 bricks were too big for my 18"' grill, so i took one brick, broke it in half.
2. I used the next smallest grate I could find, the grate for a Smokey Joe grill
3. That set-up gave me about an extra 1" of clearance.
4. my 4.5 lb bird was still too big! at first, it touched the top of the grill. But, it seemed to shrink as grilling went on. If you have this set-up, you might try to use a smaller bird...
5. you really have to rub the chicken up good. I'm using Steve's "How to Grill" book, and it's great, but the amount of rub it suggests is quite conservative.
6. 1 hr 15 minutes seemed to work pretty good, and I threw in some extra coals on either side at the 30 minute mark.
Anyhow! here are some pictures, thank you again!!