Rated 5 out of 5 stars

To get this to work in FF3:
1. Download the version 1.0.4 from the download archives (Click on "See all Versions") by right clicking on the "Add to Firefox" icon and select "Save Link As..." and download the file to the desktop.
2. Change the extension of the file from xpi to zip.
3. Double-click on the zip file and drag the install.rdf file to the desktop. (Leave this window open)
4. Open install.rdf with notepad. Search for 2.0 and replace with 3.0 and save the file.
5. Drag the file from the desktop into the zip file and replace the original file.
6. Close the zip file window and change the extension from zip to xpi.
7. Double click on the xpi file to install in FF3.

This worked for me and hopefully for others. It did take 2 restarts before it started working, though. Update: Turns out that the quotes don't update automatically as in FF2. However, you can manually update the quotes.