Yes, that's the diagram Q.G. was referring to -- I remember corresponding with him at the time because I'd recently acquired an SWC myself. IIRC he suggested I think of two square "cones" -- one projecting out of the lens to the subject, and the other projecting out of the viewfinder. With the subject at infinity, the five inch distance between lens center and viewfinder center, and the other distance noted on the diagram, become immaterial; the closer the subject is to the lens, the more the four noted distances at bottom, sides and top come into play. So yes, if you're shooting a subject at 6 feet, best tip the camera up slightly so the central point of your imagined photo is below visual center of the viewfinder.
One other handy focusing/framing calculation: you can imagine that the SWC captures a square image having each side 1.5 times the lens to subject distance. So, for example, if the subject is at 6 feet (and the lens is properly focused at 6 feet), the negative will capture an image 9 feet on a side around your subject. Turning the equation around, if you were photographing a person who is 6 feet tall, you could do so by taking the picture from 4 feet away from the subject -- probably pointing the camera at their navel, but you get the idea. Keeping this in mind is very useful in fast-moving situations -- with your camera focused at 10 feet, you can imagine that you're swinging a huge square frame 15 feet on a side. That's a pretty big field of view at 10 feet!
