Whisk together the honey, marmalade, mustard and whiskey in a medium bowl until completely combined. Using the Instant Pot® metal insert as a guide, trim the ham to fit; reserve the trimmings for another use. Place two 24-inch pieces of twine criss-crossing one another on a clean work surface and place a 24-inch piece of heavy-duty foil over the top of the twine. Place the ham cut-side down in the center of the foil. Fold the corners up over the shank end (the narrow end of the ham bone) so that most of the ham is covered with foil. Take the 2 ends of one piece of twine and tie them into a tight knot around the ham. Repeat with the remaining twine so that you have 2 twine handles to support and lift the ham.

Set a rack inside the pot and add 2 cups water. Using the twine handles, place the ham inside the pot. Fold open the foil corners so that the ham is exposed and pour the honey mixture over the ham. Fold closed the foil corners so that the ham is covered. Follow the manufacturer's guide for locking the lid and preparing to cook. Set to pressure cook on high pressure for 10 minutes (see Cook's Note).

After the pressure-cook cycle is complete, follow the manufacturer's guide for quick release and wait until the quick-release cycle is complete. Be careful of any remaining steam, unlock and remove the lid.

Lift the ham out of the pot, place in a large bowl and carefully drain the glaze and cooking juices; transfer the ham to a rimmed baking sheet, cover with foil and let sit until ready to glaze.

Remove the rack from the pot and discard the water. Place the pot back in the base, set to saute on high and add the glaze. Cook until reduced, thick and syrupy, about 25 minutes. Brush the glaze over the ham and inside each slice; serve.