Why pay for another gadget from Rockler and endup with an inferior product? The "Jig" probably is used with the crown moulding standing up-side-down on the miter saw. This requires fixtures on both sides to hold the moulding in the right position. I have used this technique and constantly had things shift and go outof alignment.
A much better way is to cut the moulding lying flat on the saw bed and set the miter and bevel angles as needed. After all that is what a compound saw was designed to do.
For those of you who want a neat Excel spreadsheet with lots of pictures, suggestions and easy ways to find the required saw settings drop me an email and I will send you my Excel program (no charge, no cost, no gimmick!!)