This is one of the cases in which I was able to reuse a pin that was broken internally but not externally, simply by pushing it back into place and running a wire from the piece left inside.

Make sure not to leave large lumps of protruding solder like the one here. I ended up having to slim it down, since it touched the metal housing of the connector when I put it back together.

Hopefully when you reassemble your EOS 20D, you won't be getting the "Err CF" message anymore.