if the ns is the gateway of your LAN, then all can be imagined, and really simply. But it is something really specific....for example when you download the centos repository the link is
rsync --progress -aHS --partial --delete-after --exclude debug/ --exclude isos/ --exclude i386/ rsync://distrib-coffee.ipsl.jussieu.fr/pub/linux/centos/6* /var/lib/repository/fr2.rpmfind.net/linux/centos
if you miss the '*' you cannot download all the symlinks and you will have 404 errors.
what we can provide is some fields
url to download
domain to match in local
and create automatically the virtualhosts. However the pointer should be adjusted manually