Make the crust: Preheat the oven to 350 degrees F. Combine the graham crackers, sugar and salt in a food processor and pulse until the graham crackers are finely ground. Add the melted butter and pulse until moist. Press the crumbs into the bottom and up the side of a 9-inch pie plate; bake until set, 18 to 22 minutes. Transfer to a rack and let cool completely.
Make the filling: Combine the pineapple, cream of coconut, rum, lemon juice and salt in a blender and puree until smooth. Pour into the prepared crust and freeze until firm, about 6 hours. Top with shredded coconut. Serve with whipped cream and cherries.