(K)ubuntu KDE3.5 Repository Installation Instructions
1. Add these lines to your /etc/apt/sources.list file:
For Maverick [STABLE] (4 lines):
deb http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity/ubuntu maverick main
deb-src http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity/ubuntu maverick main
deb http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity-builddeps/ubuntu maverick main
deb-src http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity-builddeps/ubuntu maverick main
For Lucid [OLDSTABLE] (2 lines):
deb http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu lucid main
deb-src http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu lucid main
For Karmic [LEGACY] (2 lines):
deb http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu karmic main
deb-src http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu karmic main
For Jaunty [LEGACY] (4 lines):
deb http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu jaunty main
deb-src http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu jaunty main
deb http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu intrepid main
deb-src http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu intrepid main
For Intrepid [LEGACY] (2 lines):
deb http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu intrepid main
deb-src http://ppa.launchpad.net/kde3-maintainers/ppa/ubuntu intrepid main
2. Add the GPG signing key:
sudo apt-key adv --keyserver keyserver.quickbuild.pearsoncomputing.net --recv-keys 2B8638D0
3. Install KDE 3.5:
sudo apt-get update
sudo apt-get install kubuntu-desktop-kde3
There is a mailing list available here. I strongly suggest you subscribe to the low traffic announce list so that you can receive notifications of scheduled upgrades, etc.