To prepare crust, combine crumbs, margarine, and sugar in a mixing bowl. Press mixture firmly in a 9" springform pan. Spread crumb mixture evenly in pie pan. Chill 1 hour, or until firm. Or, bake in a 375 oven for 10 minutes or until edges are brown. Cool on rack before filling. To prepare filling, completely dissolve gelatin powder in boiling water. Stir in rum extract. Combine cold water and ice cubes to make 1 1/4 cups. Add gelatin, stirring until slightly thickened. Remove any unmelted ice cubes. Fold in whipped topping, pineapple, and coconut. Blend until smooth. Chill until mixture mounds. Spoon into crust. Chill 2 hours.