Thanks for your reply Ernest.
If Maxon can be talked into to adding a 'point mode' to the camera calibration tag I think it would help make C4D a much stronger application in the arch viz world.
The 'pin' in the current configuration is used for defining a single reference coordinate only, you can't create another pin. If you could create multiple pins and generate a camera position from them, we would essentially have the system I'm hoping for.
I downloaded a trial of 3DS max the other day and tested the 'Campoint' camera match tool, and it matched one of my 3D scenes to the background image flawlessly, with a camera error of around 0.5. Previously I'd tried at least a dozen times to composite the same image in Cinema 4D using the camera calibration tag, with highly variable results each time and no real success.
The fact that an old 3rd party plugin from pre-R14 had the same point-matching functionality as today's 3DS makes me hopeful that it could relatively easily be introduced by Maxon, or re-created by another 3rd party developer (hint hint, all you clever programmers out there!)