Combine first 13 ingredients in a medium saucepan. Cook mixture, uncovered, over low heat, 20 minutes, stirring occasionally. Remove bay leaf, and discard.
Thread roast on a spit; secure tightly with prongs at each end of spit. Make sure roast is properly balanced to avoid strain on motor when spit is turning. Insert meat thermometer into thickest part of roast, being careful not to touch fat or spit. Place spit on rotisserie 4 to 6 inches from medium coals. Grill roast 4 hours or until meat thermometer registers 170°, basting frequently with sauce during last 30 minutes. Remove roast from spit; allow to stand 15 to 20 minutes before slicing.