Mix first 4 ingredients. Place half the mixture in a 5-qt. slow cooker; top with half the ham. Repeat layers. Cook, covered, on low until heated through, 3-4 hours., Using tongs, remove ham from slow cooker, leaving pineapple mixture behind; keep warm. In a saucepan, mix cornstarch and water until smooth. Stir in pineapple mixture; bring to a boil. Reduce heat; simmer, uncovered, until mixture is slightly thickened, stirring occasionally. Serve ham, pineapple mixture and, if desired, cheese on rolls.