The language settings are slightly different for console and for your graphical environment (Gnome, right?). Anyway, I thought you could select the language (French) during Ubuntu installation, right? Was it not in the list?
The language addition would be easier to accomplish if you had internet. Anyway it works even if the machines don't have it, if you can fetch the packages manually. You'll need the language-pack files (that you have already, as .deb files specific for Ubuntu), their dependencies (the files the packages need to have before they install - as .deb files too) and at least in Ubuntu 6 there were language-support packages too. Well, you can start off with the language-pack files. To install plain .deb files,
Code:
dpkg -i filename.deb
If your file A wants to have file B installed before it, and B wants A before it, you could probably just put them both in the same dpkg install command and it should install them both without a hitch (at least thats how it works on many other package managers). So, if you have all the needed language .deb packages in one directory (and there are no other .deb files there),
which hopefully works (* should be expanded to match every .deb file in the directory, and then dpkg -i run on them).
Note that you may have to run the language configuration program after this.
Your Gnome (or whatever you use) may have one language in use (selectable in the GDM login manager before giving password), and your console may use another language (locale). This
shows your current locale settings.