SPRINKLE gelatine over 1/2 cup chilled coffee in bowl; let stand 5 min. or until softened.
WHISK egg yolks, 1/2 cup sugar and 3/4 cup coffee in top of double boiler. Cook and stir over hot water until thickened. Stir in gelatine mixture and lemon juice. Pour mixture into large bowl; refrigerate 20 min. or until thickened, stirring after 10 min.
BEAT egg whites in large bowl with mixer on high speed until foamy. Gradually add remaining sugar, beating until stiff peaks form. Gently stir into coffee mixture. Spoon into crust.
REFRIGERATE 4 hours or until firm.