mkdir centos-cd1 cd1
sudo mount /dev/cdrom centos-cd1
rsync -a centos-cd1/* cd1
cp centos-cd1/.discinfo cd1
sudo umount centos-cd1

cd ~
mkdir testdb
rpm --initdb --dbpath $PWD/testdb
rpm --test --dbpath $PWD/testdb -Uvh cd1/CentOS/RPMS/*.rpm

cd cd1
createrepo --baseurl="media://1142383043.889895" -g CentOS/base/comps.xml CentOS/RPMS/

Note: Make sure the number in --baseurl corresponds to the first line in the file cd1/.discinfo. Should you have trouble with this command try using absolute path names.

cd cd1
export PYTHONPATH=/usr/lib/anaconda
export PATH="$PATH:/usr/lib/anaconda-runtime"

# Write CentOS/base/hdlist and hdlist2:
genhdlist --hdlist /home/test/cd1/CentOS/base/hdlist --productpath CentOS /home/test/cd1

Note: Absolute path names are required for the command genhdlist to work properly.

cd cd1
pkgorder /home/test/cd1 i386 CentOS > /home/test/cd1/pkgorder.txt

pkgorder is only necessary if you're going to split up the tree onto more than 
one CD/DVD.

genhdlist --withnumbers --fileorder /home/test/cd1/pkgorder.txt \
--hdlist /home/test/cd1/CentOS/base/hdlist --productpath CentOS /home/test/cd1

cd ~
mkisofs -R -J -T -no-emul-boot -boot-load-size 4 -boot-info-table -V "sipX 3.4" \
-A "Created on 8/6/2006" -P "SIPfoundry" -p "SIPfoundry" -b isolinux/isolinux.bin \
-c isolinux/boot.cat -x "lost+found" -o sipx.iso cd1

Did you compose your tree manually?  If so, you need to move all the rpms up a 
level into just Fedora/ and you need to get rid of the base/ directory.  
base/comps.xml was used by buildinstall to create the repodata, however now 
the compose tool needs to create the repodata before buildinstall is ran, and 
it has to reference a comps file wherever it is.  createrepo will copy that 
file into the repodata/ directory.

> So comps.xml is no longer used?

The file in base/ is not used anymore.  A comps file is still needed when you 
do createrepo, but that comps file can live in any location, even outside the 
tree.  Createrepo makes a copy of it in the repodata/ directory in the tree 
and that is what is used by everything.