Ron Francis Wire Works offer a clamp on unit. I have one in my 36 coupe (original column/steering wheel) and it does not look too out of place. It is cleaner than the one Frisco posted, but I'm sure it will be a few bucks more.
Ron Francis also offers lighted push buttons that are fine as well as a toggle switch option. The toggle switch option can be installed on the dash lower lip and is almost invisible, but not as convienent as the clamp on or push buttons.