I use the exact same finder on my smaller Panasonic Lumix DMC-LX5, which provides for directly setting zone focus in the manual focusing screen. In actuality, the LX5 does a better job of emulating a rangefinder than the GF1, in my opinion. It has a great scale to show the focus distance and depth of field, will allow you to lock the zoom at any focal length and the f-stop at any setting. It is a super-quick little camera for street photography.
(Click Here) to see my post on my LX5 street kit.
I will give dixeyk's approach a try. I think the main differences are in what each of us is trying to achieve. He's working toward quick response pinpoint focus and capture, while I'm working toward large depth of field, quick response street photography with a rangefinder camera.