gesticulate is a Firefox add-on that adds support for mouse gestures (currently only rocker gestures). If you're simply looking to install the add-on, you should look on AMO instead.
First, make sure you have Firefox 58 or greater. Then go to about:config and
set ui.context_menus.after_mouseup to true. This will ensure that when you
start a gesture with RMB, you'll be able to complete the gesture instead of
being interrupted by the context menu.
If you'd like to build the .xpi from the latest master, simply run the following:
$ make packageNote of course that the resulting add-on is unsigned, and likely won't work on release versions of Firefox.
This add-on is licensed under the Mozilla Public License, version 2.0.