How to Make It Work: Editing an Add-On's Compatibility Rated 5 out of 5 stars

As previously mentioned, this article tells you how to edit an add-on's max version.
http://kb.mozillazine.org/Editing_an_add-on_to_change_its_compatibility

It's a lot easier than it looks; takes about 30-60 seconds.

Simplified steps:
1. Download the aarvark add-on
2. Open it with 7-zip (free) or another archiver
3. Extract "install.rdf" and open it in notepad
4. Look for <em:maxVersion> and change the version number to whatever you want.
5. Save and replace it back in the archive
6. Install it in firefox

Almost easier than using Aardvark itself!
Works with any add-on / extension too.