I found this information at the Internet but I am not sure it will work. What about the taste? Will it work if we add Splenda (or any other flavoring)?

Sugarless Frosting
Date: Thu Jan 1 09:55:29 1998
Message:
I don't know if this is what you are looking for nor do I know the exchanges for the following recipe but it is sugarless:
Yield 2, 9" layers;1 med loaf; or 16 large cupcakes

1 1/4 cup corn syrup (light)
1 tsp baking powder
3 egg whites
2 tsp vanilla

Boil the corn syrup in saucepan over direct heat untill it spins a thread when dripped from a spoon.( I guess this is soft ball)--Beat the egg whites untill they are foamy, then add the baking powder and beat them again untill stiff.

Add the corn syrup slowly while beating (the egg whites) vigorously. Add the flavorings and continue beating until the frosting is stiff and stands in peaks. I have not tried this frosting yet,so I can't guide you but if you have sucess with it let me know.