Hi,
You can use up2date command under RHEL 4 ES/AS. up2date command always installs stable version. Remember latest may not be the good for production server. On a related note if you are ready to take risk and want to install latest version goto
Rpmfind mirror and download all RPMs for RHEL4 doing this will removes warranty covered under redhat and RHN.
Hope this helps. If you have more questions please reply back
