Ubuntu packages are the same for Kubuntu, Ubuntu and Xubuntu. They differ only by the default packets installed, every extra packet you get are all the same. You can use apt-get:
Code:
apt-get install packagename
or
aptitude or
synaptic or something else, depending on which one(s) you have installed. If a package of that name (no need to insert version numbers) is found it's installed, if not then you get a message saying it. You can also find the Ubuntu-specific .deb binary files from the net, but then make sure they are
Ubuntu .deb files and not just some other Debian/Debian-like .deb files.