Combine first 3 ingredients in a bowl; stir well. Cover and let stand 30 minutes. Drain, reserving Madeira. Combine prunes, apricots, 1/4 teaspoon salt, and rosemary; stir well, and set aside.
Trim fat from pork. To butterfly pork, slice loin lengthwise, cutting to, but not through, other side. Open the halves, laying pork flat. Slice each half lengthwise, cutting to, but not through, other side; open flat. Place heavy-duty plastic wrap over pork, and flatten to an even thickness, using a meat mallet or rolling pin. Spread prune mixture down center of pork to within 1/2 inch of sides.
Roll up pork, jelly-roll fashion, starting with short side. Secure at 2-inch intervals with heavy string. Sprinkle pepper and remaining salt over pork.
Place pork, seam side down, on a broiler pan coated with cooking spray, and insert the meat thermometer into thickest portion of pork. Bake at 350° for 1 1/2 hours or until thermometer registers 160°, basting frequently with reserved Madeira.
Place roast on a serving platter; let stand 15 minutes before slicing.