Simple way to update kickstart RPM files?

I have a kickstart server with the files copied from the CentOS
5.5 DVD's "CentOS" directory to a "CentOS" directory on the
server, accessed by ftp during kickstart.

On a target built by this system, I did a yum update, and over
100 packages were updated.

I would like to merge the updates back to the kickstart server.

But I don't see a simple way to just throw the *.rpm files (as
grabbed from yum's cache) into some "updates" directory and the
kickstart will do the right thing and resolve dependencies and
install the latest.

I would rather the updates just get installed in the first place,
instead of having to take a second pass to do some kind of yum
update method.

Is there an elegant way?