I have also posted this article on the FreeIPA.org project wiki which is linked here
Before I start, I would like to give a great deal of thanks to Mallapadi Niranjan at Red Hat for assisting me with the troubleshooting of this setup. Without his help, I would not have been able to provide this level of detail in this document.
The below details will walk you through how to add a Red Hat Enterprise Linux 6.2 system to an IPA domain, and then configure Squid to allow single sign on web caching.