I'm pretty sure that movies weren't "scanned" as we know it today. They were telecined. I could be remembering this wrong (I've only had very limited experience with telecines and they were mostly through correspondence) but these telecine machine were programmable. So you'd go through the film and punch in timecode in the computer and tell it to up the contrast to so much percent or change the color - whatever. Once you've gone through the whole film and your data is set, you'd hit record and do a realtime transfer to video tape.

I would think the same thing would apply to Pan and Scan. You program the machine to pan and scan where and when you'd want it to.