A person sitting in a chair will be difficult. You could find a picture of a person sitting in chair and use the same method with a box but it won't look the same. There's too much depth missing. It will only work if you can set the point of view (camera) exactly in front of the picture-box, so no side deviation. That it works with a (standing) person is because there's very little depth to a person if seen from the front. There you have a little leeway in the camera angle.