The first thing to do is go and download this plugin (written for Pidgin, but don’t let that put you off) created by Eion Robb.
Next, you will need to follow these instructions which first appeared on Ubuntu Forums. Enter them into the terminal as follows.
sudo mv attachment.cgi?id=20810 /usr/share/telepathy/managers/haze.manager
sudo mv attachment.cgi?id=20811 /usr/share/mission-control/profiles/bigbrownchunx-facebookim-haze.profile
Now restart Empathy and you should be able to add your Facebook account.