If you search this forum you will see that the easiest way to fit the Corbeaus is to use Elise S1 subframes. For the driver's side you can fit different lateral brackets as they bolt on - but not in the same place so another complication and the brackets are harder to find these days.
PAX side the VX brackets (and the S1) are welded. If you are good at metalwork and have the time you could make your own brackets and weld them on but needs a finger metal folder IMHO!
So, S1 frames favourite, not that easy to get and it's still not an out the box fitment as you need the longer special bolts (Corbeau seats have the metal thread deeper in the seat shell) and usually a bit of modification to the front retaining bolt holes in the frame - relatively easy, plus packing washers/spacers - see Mark Verboom postings.