Here's a recipe I've been using for quite awhile:
1 16 oz. can sliced beets, drained, reserving juice
1/4 cup beet juice
1/4 cup Splenda
2 tsp. cornstarch
1/4 cup vinegar
1 Tbl. reduced calorie margarine (I use Promise light)
In a medium saucepan, mix the beet juice, Splenda, cornstarch, vinegar and margarine and stir until thick. Add drained beets and stir until they are hot throughout.
Or course, you can use whole beets, but I think I might warm them in the microwave first, since prolonged heat may affect the Splenda.