Cut top off pineapple at the shoulder, scoop out flesh from the top to leave a small cavity. With a thin sharp knife cut down carefully just within the skin right around the circumference until the bottom is almost reached. Insert the blade 1 inch from the base working it around in both directions to loosen the inside flesh. Cut flesh into four segments from the top and remove one at a time by pressing pineapple base stem and removing the wedge with a fork. Cut away the hard center core. Cut flesh into 1/2-inch wedges and place in a bowl.
Place rum and sugar with pineapple and allow to macerate in the refrigerator.
Deep freeze pineapple shell.
Mix ice cream with chopped nuts. Mix instant coffee with 2 tablespoons boiling water. Combine with ice cream.
Place alternative layers of coffee nut ice cream with rum flavored pineapple until you reach top.