If you're wondering which LCD Viewfinder would fit the 60D LCD screen, it would be the same aspect as the T2i. You can find some good ones here: http://cheesycam.com/best-new-view-finder-t2i-60d-5d-mark-ii-7d-nikon/
Well first I want to point out that I don't suggest mounting an LCD View Finder on the Canon 60D while the LCD is swung out. Adding pressure to this swivel can damage your LCD connection. If you choose to use the sticky metal frame type of mount, then you'll lose the functionality of swiveling your LCD back into the camera body for protection. Most people can live with that, but others can't. Here's an easy solution to add a sticky frame without having to touch the LCD.
Grab a thin piece of PolyCarbonate plastic. With a thin enough piece you can bend it around the Canon 60D and 'pin' it between the spaces above and below the LCD screen. Polycarbonate can be thermal set, so a simple blow dryer or heat gun is all it takes to shape it. Once it cools down, it will maintain the shape. Look around for some old product packages, these hard plastic cases might be the type of plastic you need.
First I measured my shape by cutting and bending out some cardboard, then transferred that length to my plastic piece. Plain scissors is all that’s needed to trim the lightweight plastic.
I found a piece of steel that’s about the same thickness as my LCD. I clamped it down, heated it up, and just pulled it over by hand. Hold the position until it cools down. Do the other side and you’re pretty much done.
This plastic piece squeezes in between the LCD and provides a very very tight fit. Pulling the VFinder off of the metal frame cannot remove the plastic from the LCD. Again, I wouldn’t recommend using a View Finder while the LCD is swung out.
[Update] This is what the Metal Frame looks like when placed over a GH2. This is the T2i 3:2 version and it more than covers the area needed to be magnified.
(above) Panasonic GH2 with Metal Frame Attached. Just a few mm oversized, but everything is in perfect view.