Preheat oven to 350 degrees. Bake pie shell according to package directions; transfer to a wire rack to cool completely. Keep oven on. Spread coconut on baking sheet (preferably air-cushioned sheet). Bake until toasted, stirring occasionally, about 5 minutes. Transfer to small bowl. Set aside. To make toppings, place vanilla wafers in zipped-type plastic bag; seal. With rolling pin, crush to coarse crumbs. Add to coconut; mix well. Set aside.
Cut each banana into 1/4-inch-thick diagonal slices. Set aside. In large, deep sucepan, combine sugar and cornstarch. In large bowl, whisk egg yolks to blend, then whisk in soymilk. Whisk 1/2 cup milk mixture inot cornstarch until smooth, then whisk in remaining milk mixture. Bring to a boil over medium-high heat, stirring constantly with a whisk or wodden spoon and reducing heat if necessary. Boil 1 minute, then remove from heat. Stir in lemon juice and vanilla. Mix in bananas. Pour filling inot cooled pie shell. let stand 10 minutes to cool slightly. Refrigerate until completely set, 6 to 8 hours. Just before serving, spinkle with coconut crumb topping.