Mohamed Mahmoud has made an updated version of his extension, and made a new and faster and easier installation guide for google chrome with the new Tampermonkey extension!
I installed the new extension by Mohamed on google chrome in under 1 minute with just a couple clicks!
Firefox users still have to use Greasemonkey.
Check out Mohamed’s blog for installation guide: http://press-share.blogspot.no/2013/01/facebook-chat-emoticons-by-mohamed.html
If you already have Tampermonkey/Greasemonkey, go here to install the script: http://userscripts.org/scripts/show/140346