I have a Redhat Enterprise 4 workstation which cannot be connected to the internet. I have a subscription to Redhat and I can get the new ISOs but I'd rather update than have to rebuild the system again. I know that Fedora allows you to build your own repositories (which I have done) but you can't download the updated packages for Redhat Enterprise (or at least I haven't figured out how yet). Has anyone been able to build a repository for Redhat Enterprise and build a repository CD/DVD for local upgrades?

If you're just "updating" why not run the up2date to do it? No ISOs required.

Do you instead mean "upgrade" from 4 to 5 perhaps?

I am just trying to update, for example from baseline Redhat Enterprise 4 to Redhat Enterprise 4 Update 4. Remember, I cannot hook the computer to the internet, so "uptodate" won't work under its normal configuration. I would like to construct a local repository to point the "uptodate" program instead of the internet. I was thinking of taking the RPMs from the ISO CDs and trying to build a repository but I don't know what the chances of success will be.

Sorry missed that you couldn't do internet.

You can configure sources in:
/etc/sysconfig/rhn/sources

It has an example line for using local directory as repository. I did it once to save from having to run up2date downloads on multiple servers but seem to have lost the config.

The relevant lines in sources file:
### an local directory full of packages
### format
#dir my-favorite-rpms-i386-9 /var/spool/RPMS/


It may be able to setup an intranet repository as well but I haven't done that. There is a man page for up2date that talks about configuration as well.