You can use sugar-free Jello to replace regular Jello in most recipes.
At present you can buy the sugar-free Jello in the following flavors:-
You might need to try a few stores if you're after a particular flavor tho' - so it's probably a good idea to buy it when you see it in plenty of time for Christmas.
You can find dozens of Jello recipes at the Kraft food site online here.
The discovery of a new dish does more for the happiness of mankind than the discovery of a star.
Jean Anthelme Brillat-Savarin