In my macro photography work I use a reversed 28mm lens which gives me a razor thin DOF and it can be rather dizzying to use the viewfinder sometimes so I was wondering if a script for a range finder could somehow be implemented so that I could track how close I am to the focal point while in live view mode. Alternatively I suppose that a range finder script could be useful for other applications as well.
I don't think its possible for lenses that aren't electrically connected. Even on the ones that are the distance reported is not very accurate.