Combine first 6 ingredients in a medium saucepan, stirring well; bring to a boil. Reduce heat, and simmer, uncovered, 5 minutes; stir frequently. Remove sauce from heat, and set aside.

Trim excess fat from ham slices. Grill over medium coals 20 to 25 minutes or until desired degree of doneness. Turn ham slices and baste every 5 minutes with reserved sauce.

Grill pineapple slices over medium coals 1 minute on each side. Garnish ham with pineapple, and serve with remaining sauce.