In a medium saucepan, heat bourbon, honey, molasses, and marmalade over low heat for 15 minutes or until reduced by half, stirring occasionally. (When measuring honey and molasses, spray measuring cup with nonstick cooking spray to keep measurements accurate.) Set aside.
With a sharp knife, cut a diamond pattern on the fatty part of the ham. Stud whole cloves in each diamond, at points where lines cross. Spread half of the bourbon glaze over the ham and roast for 30 minutes, uncovered. Baste occasionally with remaining glaze and continue to roast for another 15 minutes. Let ham stand for 20 minutes before slicing.