I'm new at this large format malarkey, but I've taken to attaching my focusing cloth using Velcro. You can buy velcro in sticky strips from any home supplies type store in the highstreet - perfect for this, just stick one half to the camera and the other half to the inside of the cloth, and voila!
(It's also dead handy for other stuff - this may sound tragically like 'Readers Digest Top Tips', but... If you stick a strip of Velcro along something like the edge of a shelf, or on a convenient edge of your camera, and then stick small squares of the matching-half-of-Velcro to your lenscaps and other wotnots you need never lose them in the studio again...)