In a mixing bowl, empty sugar-free jello mix and pour the water over it and let it sit while you get the other ingredients organized.
Now my usual sophisticated cooking technique--which is to say, dump everything into that mixing bowl. Blend until smooth.
Pour into 4 ramekins and let it set.
The most important thing about getting this recipe right, is to BE PATIENT and make absolutely sure the gelatin is completely dissolved in the water before you start. If you don't do this, you will have granules in your mousse and that will not be a good thing.