There is an easy solution:

Follow http://superuser.com/questions/290280/how-to-download-chrome... in order to download the crx file manually.

Then unzip it and vet it manually to be clean.

Copy it in a folder, enable extension developer mode in Chrome and install the local copy of the extension.

No autoupdate, everything's fine.

Unfortunately Google plans to disallow local extensions, which is a major disaster and very evil: http://thenextweb.com/google/2013/11/07/google-block-local-c...

What happened to that?