In top of double boiler, soften gelatin in water. Add egg yolks, slightly beaten, and salt. Place over boiling water and cook, stirring constantly, until mixture thickens, about 7 minutes. Remove from heat and stir in unthawed frozen lemonade. Stir until mixture thickens. (The custard usually sets fast and needs no chilling.)
Beat egg whites to soft peaks; stir in sugar, 2 tblsp. at a time, beating well after each addition. Beat until stiff peaks form. Fold into gelatin mixture; then fold in coconut, reserving a little to sprinkle on top of pie. Drop a spoonful of mixture into pie shell. It should mound. If it doesn’t, chill, stirring a few times, until it will mound. Turn into pie shell and chill pie until firm before cutting.