Daniel, alldata.com seems to have a lot of itnerior trim removal processes that I don't remember seeing in the W126 MB CD manual. It guides you through removal of the door panels and headliner at the very least. There's a section on removing the cubby above the AC vents but nothing on removing the optional phone in the same location. I'd say it's worth at least a year.
To the point, however, I didn't find an answer to the question posted above.