Hi,
Looked at the code, this specific extension relies on API stuff mostly, which is quite different in Chrome and Firefox. For example, the options page, or how browserAction (the icon top there in the right) is located vs Widget (in addon bar down there at the bottom). I've done both Chrome and Firefox extensions, almost all my projects here are extensions. So quite know the challenges ahead.
Would be glad to help to port this extension. If there are any questions, let me know.
Yasser