CentOS 5 - realtime patch

Where can I download precompiled CentOS 5 kernel including realtime patch? Or I need to compile it myself (if yes, how to do that)?

While I own a few RHEL MRG licenses, I've started using the FREE realtime recompile of http://www.redhat.com/mrg/">Red Hat MRG from Scientific Linux to convert my CentOS 5 servers to realtime. You can view the Scientific Linux MRG distribution at: http://glitesoft.cern.ch/cern/mrg/slc5X/x86_64/RPMS/

In order to install, I create a small repo file named slc5x-mrg-realtime.repo and drop it in /etc/yum.repos.d. The file contains:

[slc-mrg-realtime]
name = SLC5X - MRG Realtime
baseurl = http://linuxsoft.cern.ch/cern/mrg/slc5X/$basearch/RPMS
enabled = 1
protect = 0
gpgkey = http://glitesoft.cern.ch/cern/slc44/x86_64/RPM-GPG-KEYs/RPM-GPG-KEY-cern
gpgcheck = 1

From there, I can simply run yum grouplist and see the MRG component groups:

   MRG Realtime
   MRG Grid
   MRG Management
   MRG Messaging

A yum groupinstall "MRG Realtime" && yum install kernel-rt-devel gives me everything I need for realtime operation. You can also just pick and choose the files you want from the distro's rpm listing page at: http://glitesoft.cern.ch/cern/mrg/slc5X/x86_64/RPMS/

Another option is to perform a recompile of Red Hat's SRPMS available at: http://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/RHEMRG/SRPMS/

It's the standard rpmbuild --rebuild package.srpm process. This takes more time, but I've done this successfully as well.