In a saucepan, combine sugar and cornstarch. Gradually stir in water, mixing until smooth. Cook and stir over medium high heat until thickened and clear. Quickly stir in egg yolks. Bring to a boil; boil for 1 minute stirring constantly. Remove from the heat, stir in 1/3 C. lemon juice, salt and butter. Cool for several hours or overnight.
In a mixing bowl, blend condensed milk and cream cheese until smooth. Stir in pudding mix and remaining lemon juice. Fold into chilled lemon filling. Divide and spoon into baked pie shells. Refrigerate for several hours. Garnish with whipped cream and lemon slices.