Hi there.
You can set up a local repository, or you can set up a local mirror... There are several guides on how to set up a mirror but if your bandwidth is a problem, you just want a local repo.
Change location path and...
location="/path/to/unchanging/location/which/is/also/added/to/fstab"
mkdir /$location/debs
mv /var/cache/apt/archives/*.deb /$location/debs
mv /usr/pluto/deb-cache/*.deb /$location/debs
dpkg-scanpackages /$location/debs /dev/null | gzip -9c > Packages.gz
cp /etc/apt/sources.list /etc/apt/sources.list.repo.backup
echo "deb file:///$location/debs/ ./" > /etc/apt/sources.list
apt-get update
Here is the problem. In 1004, currently, when a new build happens, it builds everything. An upgrade will pull down EVERYTHING on deb.linuxmce.org, because all of the packages get a new higher number. So if you want to screw around with installs...
keep in mind that when you are doing an install, the appropriate repo's get added during the process... so you will either need to modify your install scripts, or do some sort of hack like putting a lock on the sources.list file.
I am not sure exactly what you are trying to do. I hope this helps.