Reserve 2 tablespoons crushed macaroons for garnish; set aside. Combine remaining crushed macaroons, shredded coconut, and melted butter in a medium bowl; stir well. Firmly press crumb mixture evenly in the bottom and up the sides of a buttered 9 inch pieplate. Bake at 300 degrees for 20 minutes; let cool.
Press the pineapple through a sieve, reserving 1 cup juice.l Combine the pineapple juice, pineapple, sugar, lemon juice, and salt in a medium saucepan. Cook over medium heat, stirring constantly, until the sugar dissolves.
Sprinkle gelatin over the cold water in a small bowl; let stand for 1 minute. Add the gelatin mxture to the pineapple mixture; cook over low heat, stirring until the gelatin dissolves.
Beat the egg yolks at high speed of an electric mixer until thick and lemon colored. Gradually stir about 1/4 of the hot mixture into the yolks; add to the remaining hot mixture, stirring constantly. Cook over medium heat, stirring constantly, until the mixture thickens slightly and comes to a boil. Transfer to a medium bowl, and chill until the consistency of unbeaten egg white.
Beat the egg whites (at room temperature) at high speed until stiff peaks form. Gently fold the beaten egg whites into the chilled pineapple mixture. Fold in half of the whipped cream. Pour into the prepared crust; chill until firm.
Pipe or spoon the remaining half of the whipped cream over the chilled pie. Sprinkle with the reserved 2 tablespoons crushed macaroons.