okay, this is the retarded shop tech proof method of getting your skis mounted where you want them.
First, Measure that shit out yourself, don't ask some retard to measure your two cm. back from true center, cause they are going to fuck it up.
Second, Take a big fat paint pen and draw a line across the ski where you want your midsole to be.
Last, tell the tech that the big fucking paint line across your ski is where you want your midsole to be.
Most likely they will be able to accomplish this task, and if they still fuck it up you are in a much better position to demand that they replace your skis.