This might be silly, but I wonder if anyone has tried frame/focusing the 5D using video goggles like these:

Wrap 920 (http://www.vuzix.com/iwear/products_wrap920.html)

-- peer

I have used them with a jimmy-jib before. Hard to see with light coming in from the outside. Ended up making a black hood out of neoprene, and then you look like some kind of S&M freak instead of a videographer. After that it did work pretty well (though you look weird), but at the time the resolution of those goggles was like 360p, so it was hard to focus. Ended up going with more traditional means.