Something

[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=redhat-release
tolerant=1
exactarch=1
retries=20

[base]
name=CentOS-$releasever - $basearch - Base
baseurl=http://syspackages.sourcedns.com/packages/mirrors/centos-3/$releasever/os/$basearch/

[updates-released]
name=CentOS-$releasever - $basearch - Released Updates
baseurl=http://syspackages.sourcedns.com/packages/mirrors/centos-3/$releasever/updates/$basearch/

[addons]
name=CentOS-$releasever - $basearch - Addons
baseurl=http://syspackages.sourcedns.com/packages/mirrors/centos-3/$releasever/addons/$basearch/

[extras]
name=CentOS-$releasever - $basearch - Extras
baseurl=http://syspackages.sourcedns.com/packages/mirrors/centos-3/$releasever/extras/$basearch/