Xen users - Jul 2012 - Centos 5 compile Xen doubts?

Hi.

I want to compile Xen 4.0.x on Centos 5.8, I had follow
http://wiki.xensource.com/xenwiki/Xen4.0, but once I finish this:

make xen
make tools
make stubdom

No issue here, Now what about with Centos 5.x?

I just need to rebuild centos 5 kernel with xen support?

Any tip will be appreciated, thanks.

P.S:I know that I have the gitco repo, I want to learn how to build xen.