Aside from my concerns about "could" vs. "should"; getting back to the original question of "is it possible to implement..."
The "inspect" part of PAC Manager reads values from the memory map, which is something that can be done in a chart, ditto for the sending of files via ftp required to do a firmware update. So in theory, yes, one could implement those PAC Manager functions in a custom chart triggered by various user tags. But it wouldn't be easy.
However, I'm thinking Robertson might have been suggesting adding such a pass-through feature in the controller -- but that would essentially poke a hole through (defeat the main purpose of) the very network setup that started this discussion.
I like where philip is heading with his VPN-ing, etc. Keep those good ideas coming!