Jeff,
The usual setup is for the wheel rim to be laced up to the hub, then between every other spoke there is a short spoke lacing the wheel rim to the belt rim. These keep the belt rim concentric with the wheel. You should then have small plates, each with 2 nuts and bolts, to clamp the belt rim against the main spokes, to keep the belt rim running true. (there are probably 9 or 10 of these plates).
Regards,
Eddie.