Red Hat Enterprise Linux 4.0 for Linux - IS&T support page.comment out the appropriate exclusion line in /etc/yum.conf then run yum update.use yum to download the packages to local disk cache and then install them using rpm.So, there are two ways to update kernel versions: yum doesn't have the -force option available as up2date did.
The Red Hat Linux at MIT page - info from IS&T about the currently supported version.