Adjust oven rack to upper-middle position and heat oven to 250 degrees.
Heat oil in a small skillet over medium-low heat. Add whole garlic cloves and cook, stirring occasionally, until soft and golden, about 5 minutes. Remove with a slotted spoon; reserve oil.
Turn pork loin fat-side down. Slit lengthwise, almost but not quite the whole way through, to form a long pocket, leaving a Â½ inch border of unslit meat at each end. Brush cavity with some of the reserved garlic cooking oil, and sprinkle generously with salt and pepper and 1Tb. of the rosemary. Line cavity with sauteed garlic and apricots; sprinkle with cranberries. Tie loin together with kitchen twine or heavy-duty string at 1 Â½ inch intervals.
Brush meat with remaining oil, and sprinkle generously with salt and pepper. Set roast, fat-side up, diagonally or curved (so it fits) on a large, lipped cookie sheet or jellyroll pan.
Warm Â¼ cup apple jelly along with minced the minced garlic and rosemary. Brush mixture onto meat.
Roast until a meat thermometer stuck into the center registers 125 to 130 degrees. (Start checking at about 1 Â½ hours.)
Remove from oven; raise oven temperature to 400 degrees. Brush loin with pan drippings, return to oven, and continue to roast until the loin is golden brown and a meat thermometer stuck into the center registers 155 to 160 degrees, about 20 minutes longer. For even more attractive coloring, broil until spotty brown, 3 to 5 minutes.
Let roast rest 15 to 20 minutes; transfer to a carving board. Stir juices around pan to loosen brown bits. Pour through a strainer into a small pan, and stir in port wine or rum, chicken broth and remaining 2 Tbs. of jelly; whisk into sauce. Simmer until lightly thickened.
Slice pork. Serve each slice with a little sauce poured on top.