How to FireFox extension development environment setup.
Basically, you setup another profile.
You then setup that environment for development manually or using an extension that sets those parameters automatically.
Install these two extensions
Be sure to read on how to package your extensions.
zip -r ../myexample.xpi *
For more information see
Run this command line to start the FireFox profile on OSX, terminal window will display debugging information.
/Applications/Firefox.app/Contents/MacOS/firefox-bin -no-remote -P dev &