Have you tried to download the official SuSE package from the
OpenSuSE site? If you select your system in the drop-down menu (SuSE SLE-11 or SuSE SLE-11 SP1) and look for virtualbox, you will find the virtualbox-ose-3.2.6 RPM. The 1-click install method should take care of setting up the source repository and managing the required dependencies.