I've recently put together this patch to convert a vanilla centos-4 
metadata into one for centos-5.  Template works flawlessly for me.

Instructions to apply the patch:
1) wget 
http://download.openvz.org/template/metadata/centos-4/src/vztmpl-centos-4.src.tar.bz2
2) tar xvjf vztmpl-centos-4.src.tar.bz2
3) cd centos-4
4) patch -p1 < /path/to/attached/centos-5-metadata.diff
5) yum install createrepo
6) make clean
7) make rpms

If your arch is i386, the metadata rpm should now be located in:
/usr/src/redhat/RPMS/i386/vztmpl-centos-5-2.0-2.i386.rpm


Notes:
- "kernel = 2.6.18" is needed to fix the "Error: initscripts conflicts 
with kernel < 2.6.12"
- udevd must be disabled when the vps starts up


I'd very much be interested in seeing this become an official metadata 
template on openvz.org.  I'd like to get centos-5 out of the user 
contrib area.

-Chris