Preheat oven to 425.  Line pie dough with foil; arrange pie weights or dried beans on foil. Bake at for 10 minutes; remove weights and foil, and bake an additional 10 minutes or until golden. Cool completely on a wire rack.

In a saucepan, whisk 2 cups of the cococnut milk and 3/4 cup sugar together. Place the pan over medium heat and bring the liquid up to a simmer. Whisk the egg yolks together. Temper the hot milk into the egg yolks, by adding a small amount of hot liquid to the eggs and mixing them and then adding the eggs to the pot. Whisk the egg mixture into the hot milk mixture. In a small bowl, dissolve the cornstarch in the remaining milk. Whisk the cornstarch into the hot milk mixture. Bring the liquid up to a boil and reduce to a simmer. Cook the mixture, stirring constantly, until the filling is thick, about 4 to 6 minutes. Fold in the vanilla, 1/2 cup coconut, and margarine. Mix well. Pour the filling into the prepared pan and cool the pie completely.

Place egg whites and cream of tartar in a large bowl; beat with a mixer at high speed until soft peaks form. Combine 1/4 cup sugar and 2 tablespoons water in a saucepan; bring to a boil. Cook, without stirring, until candy thermometer registers 250°. Pour hot sugar syrup in a thin stream over egg whites, beating at high speed until thick. Spread meringue over pie and sprinkle with 1/4 cup toasted coconut.

*To toast grated coconut, heat a small pan over medium high heat, and cook for about 1 minute while stirring until the coconut turns golden brown.  Be careful not to burn.