Heat oven to 325 degrees. Coat 25 cm tube or bundt pan with nonstick vegetable spray; set aside. Sift flour, baking powder and baking soda together; set aside.
Beat cream cheese and margarine with an electric mixer in large bowl until well blended. Add sugar and beat until light, 2 minutes. Beat in egg substitute, egg whites, buttermilk, vanilla, lemon zest and liquor; mix well. Add flour mixture and beat until just blended.
Turn batter into prepared pan. Bake until toothpick inserted in center comes out clean, 75 to 80 minutes. Cool in pan 5 minutes before turning out onto rack to finish cooling. Dust with confectioners' sugar while still warm.
Per serving: 260 calories, 8 g fat, 4 mg cholesterol, 395 mg sodium, 38 g carbohydrates, 7 g protein