I have the same question, as I was thinking about putting a set on my 96 Cobra Convet. Have you thought about calling the company that sells them and asking them straight out how they install?
The factory piece on my car looks as though it is separate from the rest of the side of the car, which makes me wonder if it bolts on from inside the car, or inside the fender well. If it does and the new part is a stand-alone replacement, meaning that at some point I could restore the car to original by unbolting the aftermarket scoop and reinstalling the factory part, I'd probably be interested in doing it. In fact, that is the only way I would consider doing it.