Installing without a net connection will be diffcult. You can install it if you have a little bit of patience. Do the following.
$sudo dpkg -l
This will list all packages in the system. Save the output to a file using
$sudo dpkg -l >file
Now go to
http://packages.ubuntu.com search for xmms and vlc.
In the download page check whether the dependencies are installed by comparing list in file. If the dependency is not installed download the dependency. Check for the depedencies of depedency also. Download the main package. Install all dependencies and package.
There is another clever way of downloading packages and depedency automatically. Access a computer with net connection.
Use your ubuntu live cd. Add the additional resportaires in the synaptic package manager. Search for the package and click check box. Select download only. The downloaded packages and depedencies will be in /var/apt/cache . Copy to removable media and install on your system.