Add 3 ounce package lemon Jello to 1 cup boiling water. Set aside. Cream 8 ounce package Philadelphia cream cheese and 4 tablespoons concentrated lemon juice together. Blend into Jello. Set aside. Whip 1 tall can of chilled Pet evaporated milk. Gradually add 1 cup sugar. Fold into Jello mixture. Pour into prepared graham cracker crust. Chill 4 hours.