…doesn’t work for me. I eventually remembered what my ‘native’ CodePlex password was, and that worked just fine.
Of course, this turns out to be a RTFM:
Q: Why do I still need a CodePlex account?
A: We still require a CodePlex account to successfully authenticate with the source control servers.
…but it wasn’t like was plastered all over the account linking process page, or (unfortunately) mentioned on that ‘how to set up TFS client’ popup they have.