Preheat the oven to 500 degrees F. In a small bowl, combine the raisins and rum. Set aside to soak while the ham cooks, at least 2 hours. Make the spice paste by placing all the ingredients in a blender or food processor fitted with a steel blade and processing until smooth.
Using a sharp knife, score the entire surface of the ham in a crosshatch pattern, cutting down just through the skin to the flesh underneath. (If you are cutting to the right depth, the skin will spread apart a bit as you cut.) Rub the ham all over with the spice paste, pressing it gently into the crosshatch cuts. Put the roast on a rack in a roasting pan and roast for 20 miutes. Reduce the heat to 300 F. After 40 minutes more, begin painting the ham every 15 minutes or so with the maple syrup. Total cooking time should be 2 to 2-1/2 hours for medium to medium-well. To check for doneness, insert a meat thermometer into the center of the roast; 147 F is optimum.
While the ham is cooking, put the cider in a medium saucepan and bring to a boil over high heat. Reduce the heat to medium-high and simmer vigorously until reduced by about half, about 20 minutes. When the ham is done, remove it from the roasting pan, cover it loosely with foil, and allow it to rest for 20 minutes to 1 hour.
Tip the roasting pan so you can spoon off all the fat from the pan juices, then place the pan on the stove over two burners set at medium-high heat. Add the reduced apple cider and bring to a simmer, scraping the bottom of the pan to get up the browned bits. Skim any scum off the surface and season the liquid as needed with salt and pepper. Add the rum-soaked raisins and stir to combine, then pour into a gravy boat. Serve thick slices of ham drizzled with the cider-raisin sauce.