I did not check yet but did CentOS provide kernel-debuginfo RPMs like in
http://updates.redhat.com/enterprise/4AS/en/os/Debuginfo/i386/RPMS/
The debuginfo packages are not hosted on mirror.centos.org ( to save mirror space ) - they are hosted at http://vault.centos.org/debuginfo/
Not available as YUM repository? :)
Mindaugas