http://kbase.redhat.com/faq/docs/DOC-15838

How do I use yum to download source packages instead of manually downloading every single package from RHN ?

yum install yum-utils

cat > /etc/yum.repos.d/rhel-src.repo
[rhel-src]
name=Red Hat Enterprise Linux $releasever - $basearch - Source
baseurl=ftp://ftp.redhat.com/pub/redhat/linux/enterprise/$releasever/en/os/SRPMS/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

yumdownloader --source strace

cd /usr/src/redhat/SOURCES