PLACE drink mix in large bowl. Add water; stir until mix is dissolved. Add ice cream. Beat with mixer until well blended. Gently stir in COOL WHIP. Freeze, if necessary, until mixture is thick enough to mound.
SPOON into crust.
FREEZE 4 hours or until firm. Remove from freezer 15 min. before serving. Let stand at room temperature until pie can easily be cut.