From the PDF it looks like the e-center support bracket spans 2 roof cross members. 1 behind the "A" pillars and another just behind the front seats ("B" pillar area). If you do not have a sunroof, you should be able to use these to do what you are wanting. The problem you will have to figure out is dealing with the contour of the headliner.
Here is another thread posted here a while back with drawings from the SM. This one is about the sunroof, but you can see the cross member in it.
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