A long time ago we created a plugin to help integrate in the code needed to get CrazyEgg working on a Joomla website. This was for Joomla 1.5 and the code hadn't been update since, but we've finally managed to update it for Joomla 2.5 and Joomla 3.
This is also a free plugin so simply go to the downloads section of the website, navigate to the CrazyEgg section of the downloads area and download the plugin to install on your website!
Easy as that.
If you have any questions or require support, feel free to contact us and we'll help you get the plugin working on your website.