As I was just driving home, I heard a similar recipe on the radio. It was for low calorie eggnog. I think you could adapt it for pudding by decreasing the milk and changing all the ingredients to the "leaded" version.

4 cups skim milk
1 small pkg sugar free instant vanilla pudding
1 tsp rum extract (I may have that amount wrong)
1/4 tsp nutmeg

Mix all together. Makes 4 servings, 104 calories each with no fat.