Preheat oven to 350°. Stir together cookie crumbs, 1 cup coconut, and 1/4 cup melted butter; firmly press on bottom, up sides, and onto lip of a lightly greased 9-inch pieplate.
Bake at 350° for 10 to 12 minutes or until lightly browned. Remove to a wire rack, and let cool 1 hour or until completely cool.
Whisk together milk and cornstarch in a heavy saucepan, whisking until cornstarch is dissolved. Whisk in egg yolks and 3/4 cup sugar, whisking until blended. Cook over medium-low heat, whisking constantly, 8 to 10 minutes or until a chilled pudding-like thickness. (Mixture will just begin to bubble and will be thick enough to hold soft peaks when whisk is lifted.) Remove from heat; stir in pineapple, 1 Tbsp. butter, and vanilla. Spoon immediately into cooled piecrust.
Beat egg whites at high speed with an electric mixer until foamy. Add remaining 1/4 cup sugar, 1 Tbsp. at a time, beating until stiff peaks form and sugar is dissolved. Spread meringue over hot filling, sealing edges. Sprinkle remaining 1/3 cup coconut over meringue.
Bake at 350° for 10 to 12 minutes or until golden brown. Remove from oven to wire rack, and let cool 1 hour or until completely cool. Chill 4 hours.