In my experience, for the most part if something shows up as a valid part for your VIN, they're willing to do it. For example for my S, I can order the mechanical horn steering wheel and they're happy to do the retrofit. They want $2k so I'm holding off, but that's another issue.
What they balk at is when a part is not considered valid for your config (your USB hub for example).
In either case, sounds like all the more reason to let people do it themselves with the help of toolbox rather than taking up SC time as you put it.