CRUST: In bowl, combine wafers and butter. Press into 13 x 9 inch glass baking dish. Refrigerate. FILLING: In saucepan, cook gelatin, salt, coffee and milk, stirring constantly, over medium heat until hot and coffee is dissolved. Reduce heat. Stir a little coffee mixture into egg yolks, then pour egg mixture back into saucepan. Cook, stirring frequently, until mixture thickens slightly, 4 to 5 minutes. Remove from heat and add liqueur. Using an electric mixer or food processor, blend cream cheese and 1/4 cup of the sugar until smooth. Slowly blend coffee mixture into cream cheese. Chill, stirring occasionally, until consistency of raw egg whites, about 1 to 1-1/2 hours. Meanwhile, melt chocolate in double boiler over hot water. Let cool. Beat egg whites until soft peaks form. Gradually add remaing sugar and beat until stiff peaks form. Gently fold egg whites into coffee mixture. Transfer 1-1/2 cups of coffee mixture to small bowl and fold in chocolate. Using large spoon, alternately spoon two mixtures over chocolate crust. Use knife to swirl chocolate through coffee mixture. Refrigerate until firm, at least 6 hours.