I am looking at a car (non914) that has faded black leather on the side bolsters.
Can I add color back into them with some good old fashioned shoe polish?
Or would the poilish eventually make its way into my clothes?

Well, it just depends on how you do it. I have used shoe polish to reblack my seats, but if you go to an appolstry shop they will show you better stuff for doing that. If you try shoe polish make sure you get it in there very well or your cloths will get it