If it was windows machine that had no internet connection, what I would do is downloading the installers/programs on another computer, putting them on a portable media, copying them on the conectionless machine and install them. Linux does not work that simple unfortunately - though I hope you'll prove me wrong on this point.
On linux (debian), I never had the pleasure installing anything differently than through:
sudo apt-get install package_name(s)
Thing impossible without connection to the internet. Unfortunately, it's also very unclear which files are to be downloaded - and from where. Often apt downloads dozens of files which is something I'd hate to do manually.
So, is there a program that would download the files on my Windows PC with no need to do anything more than telling it package name?