The Ricoh GX-100 and 200 example suggests that you need more than 4-5 pins to connect to an EVF. Below the first picture is the hot shoe of a GR-D2, showing 4 pins, one of them larger and presumably ground. The second picture is the hot shoe and a mystery connector just below that the EVF uses, on a GX-100. The ground contacts on the GX-100 are much larger, and the socket below appears to have many parallel signal contacts, (GR-D2 photographed with the GX-100, and vice versa. Isn't the macro function on a small format digicam convenient?)
scott