I do our installs via PXE / HTTP, I go and get a post install script and run it. This way I don't have to muck around with the php scripts that generate the kickstart files for the installs.
%post mkdir -p /root/bin; cd /root/bin wget -q http://centos-4-repo1.XXX.XXX/yam/centos4-i386/install/post-install.sh sh /root/bin/post-install.sh 2>&1 | tee >> /root/post-install.log
Script on the kickstart server - post-install.sh
rm -rf /etc/yum/repos.d/*
cat >> /etc/yum.conf << "EOF" [base] name=CentOS-$releasever - Base baseurl=http://centos-4-repo1.XXX.XXX/yam/centos4-i386/RPMS.os http://centos-4-repo2.XXX.XXX/yam/centos4-i386/RPMS.os gpgcheck=0
[update] name=CentOS-$releasever - Updates baseurl=http://centos-4-repo1.XXX.XXX/yam/centos4-i386/RPMS.updates http://centos-4-repo2.XXX.XXX/yam/centos4-i386/RPMS.updates gpgcheck=0 EOF
yum -y update
J.J.