Good description of the proper way, but I have another suggestion.
Rather than trying to tell the installer how to do this properly (some won't listen and even if they do, if they don't have experience its going to be a real challenge for them to do it right!) try to find an installer that has MB experience.
The new window seals these glass places deal with come with adhesive already in place and all they do is press the glass on and its done wham bam thank you mam! The old style seals are very much demanding of skill.
My suggestion is call your local MB Indy (you do have an independent shop there in St Lois area that you have done business with, haven't you?) They usually know an installer that has done "older" Mercedes seals. Don't let them talk you into doing the job themselves at a shop unless you trust them. I saw a couple of mechanics at a shop trying to install a windshield in a 123 chassis break the customer's glass when they banged on the last corner with a hand to force it in
Good luck!