If you have the bindings just make one.
put the bindings on paper... use a pencil or sharpie to mark on a piece of paper where the holes are. on either side of the holes measure out putting a mark every 1/4 inch... Place that paper on your ski, making sure there are the same amount of marks on each size, thus meaning the holes are centered. When I did it, I just put the bindings on my ski where they looked good..... marked through the holes... measured to the sidewall to make sure it was actually close to the middle of the ski, and went.
*insert claim here*