Você precisa executar estes quatro comandos no terminal (um após o outro!):
wget -qO - http://download.opensuse.org/repositories/home:sxxxx/xUbuntu_12.04/Release.key | sudo apt-key add -
echo 'deb http://download.opensuse.org/repositories/home:sxxxx/xUbuntu_12.04/ /' | sudo tee -a /etc/apt/sources.list.d/qtck2launcher.list
sudo apt-get update
sudo apt-get install qtck2launcher