Many of us use SPAD for the Saitek Panels to wrk in P3D or (apparently) FSX Steam Edition.

I haven't tried this yet, but it sound reasonable and I think worth mentioning.
Froogle has tried it and put up a very simple guide on what to do: https://www.youtube.com/watch?v=j-Fr9igMxPQ

Hope it works for you. Will try it, as soon as I have some more time.