[ubuntu-za] add repo

[Miles]

Hi all, can someone please tell me how to add my external drives
/media/storage/packsM (Which is a rsync of /var/cache/apt/archives) as
the repo the my sudo apt-get update and synaptic and update manager will
use as the repo to do updates and installations of packages from. will
the path /media/storage/packsM work or must I have a separate partition
on the external called /media/repositories. My pc can not do unity so I
need to keep Maverick with all its packages and updates etc here in case
of needing to do a clean install for whatever reason and also be able to
install Maverick on other drives with out needing to go online to get
updates. My son is going to get the whole repo for me on an uncapped
line for me to copy to my external. Oh ya, and are all the security
updates and other updates kept at the same online repo? And is there a
difference between official downloaded repos and a backup of my
apt-cache. Thanks in advance for the help.
Miles