Mix crumbs, 1/4 cup sugar and butter; press onto bottom of 9-inch springform pan.
Sprinkle gelatine over 1/4 cup water in small saucepan; let stand 1 min. Cook and stir on low heat 3 min. or until gelatine is completely dissolved.
Beat cream cheese, remaining sugar and cocoa in large bowl with mixer until blended. Gradually beat in gelatine mixture, then remaining water and liqueur; refrigerate until slightly thickened. Gently stir in COOL WHIP; pour over crust. Refrigerate several hours or until firm. Meanwhile, melt chocolate as directed on package; use to make chocolate curls. (See Tip.)
Top cheesecake with chocolate curls just before serving.