[CentOS] Read only nfsroot and diskless booting CentOS 6?

Does anyone have any good how-to's or documentation on setting up read only root NFS for pxe booting diskless computers? A few months ago I stumbled upon an official Redhat doc through a google search(not hosted by redhat and I cannot find it anywhere on the Redhat site) written by Dave Kline named "Configuring diskless clients with Red Hat Enterprise Linux" from 2011. It seemed to be a work in progress but the steps in it did work for doing nfsroot for one diskless client only. It did not have any explanation for doing read only nfsroot or how to deal with /var for multiple systems. I know there is a file in /etc/sysconfig/readonly-root but I could not get it working correctly. I did kludge together something for /var where during the init process I created a tmpfs for /var and rsync'd a copy of /var from an nfs mount. This worked, but again I felt it was a kludge to a proper solution. 

Although I got this working for booting an old bios based Dell and a VM via PXE boot, I don't know if it will work for newer UEFI based computers. I'm just looking to boot about 20 or so small modern PC's into a stripped down gnome desktop with a few apps installed. I still have not decided on the diskless clients I want to use. I was thinking either something like the low end intel NUC or one of the small AMD APU based PC's.

David C Miller.