It is important to understand that 'waxes' and 'sealants' have the same use and really don't need to be combined.
A wax is typically a blend of natural waxes (often carnuba), polymers, oils and gloss agents. A sealant is a blend of man-made polymers, oils and gloss agents.
A glaze is used to improve clarity of the paint finish and possibly hide minor surface imperfections. It's use is most noticeable on older paint jobs, but can definately still be used on newer paint.
With all that said, to answer your question...some people use carnuba wax as a final finish over a man-made sealant. However, I would only recommend doing this if your car is more of a "show-car" or "garage queen". The reason being is that natural carnuba waxes don't last very long at all compared to synthetics and you would probably want to strip everything off for best results rather than just apply another coat of carnuba every few months. As you can imagine, this would be very time intensive.
I have been detailing cars for almost 20 years and would recommend using polish, glaze and sealant in that order. You could always finish it off with a good carnuba if you don't drive the car a lot or don't mind redoing the job every few months.
However, to each his own. Some people highly recommend natural waxes over man-made. There are pro's and con's to both methods.
Hope this helps a little...
-J.