Rated 4 out of 5 stars

It works, but it is a bit hard to use. I managed to bind a key to “Search events and tasks” so I'm happy.
You will find explanations on the official website [1] and have to search for the precise command name with the DOM explorer (Ctrl + Shift + I) [2].

[1] https://github.com/willsALMANJ/tbkeys
[2] http://kb.mozillazine.org/Keyconfig_extension#Finding_code_for_keys

This review is for a previous version of the add-on (2.1.0).