I was just recently wondering about the notion of adding a button and a buttonhole. I would never do it because I'm aiming for authenticity, but how hard would it be?Roll is a characteristic of a coat that can not be easily altered. So your coat has to be made to roll to 2. Feasibly one can add a button to a 2 buttin jacket and have "3 roll to 2" coat.
So there is nothing much to "achieving" this look, besides getting a proper garment.