python ensim-installer.py --ftp-server=download.pro.parallels.com --extra-source=http://download.pro.parallels.com/ensim/repos/fedora/4/i386/extras/ --os-source=http://archive.fedoraproject.org/pub/archive/fedora/linux/core/6/i386/os/ --updates-source=http://archive.fedoraproject.org/pub/archive/fedora/linux/core/updates/6/i386/
This will update Ensim using the archived Fedora releases.