All (?) ME7 have digital VSS input on dedicated pin.
Using that VSS input is only a matter of configuration, never seen it any other way yet.
It can take the signal from ABS CAN, from Kombi CAN or from dedicated wire.
I do not mean to scale my singular experience to your generally quantified ME knowledge
but I looked into this in detail for ME7.9.10 at some point. All stands as you say, and I found all the configuration bits I needed, the VSS pulse signal interrupt was there in the code, two different ways to get speed from CAN, everything. Only that the VSS signal through the pin did not work, the connection path for the pin on the board was missing the required components. I found it weird and went the CAN path for my purpose. There is always a chance I was looking at wrong paths on the board and I should recheck it perhaps, but now that I have the original problem solved I can't be bothered. Just saying...