hello. I also I have ubuntu lucid. and also had the same problem. the problem itself is with repositories of libreoffice only packages are available for versions 11.10, 12.04 and 12.10. you just need to remove the repository of libreoffice and add this new repository if it works:
sudo add-apt-repository ppa:ricotz/ppa
sudo aptitude update
This repository will install version 126.96.36.199. but at least this version works great.
sudo apt-get install libreoffice libreoffice-gnome
NOTE: These are official repositories. packages are made by the same who run the repository libreoffice: Rico Tzschichholz. Just in case you can check the repository Launchpad page you suggest and official page LibreOffice repository.