Place butter in a microwave-safe bowl, and microwave on low power until the butter is very soft and slightly melted. Pour in the corn syrup, honey, and molasses, and mix to a smooth, light brown mixture.
Score the ham in a diamond pattern about 1/4 inch deep with a sharp knife. With a pastry brush, coat the ham generously with the glaze. Place the ham into a roasting pan, and cover with aluminum foil, taking care not to touch the ham with the foil.
Bake the ham for 1 hour and 10 minutes (10 minutes per pound), removing the foil tent every 20 minutes to recoat the ham with glaze.
Remove the foil tent, and turn on the oven's broiler. Broil the ham until the glaze is slightly darkened, about 10 minutes. Remove ham from oven, let stand about 10 minutes, then carve and serve.