The install script will install autodl-irssi and optionally also ruTorrent, the ruTorrent plugin and any other dependencies required to have a fully working ruTorrent install.
Login to your Server as root
Ubuntu and Ubuntu clones:
wget --no-check-certificate -O autodl-setup http://sourceforge.net/projects/autodl-irssi/files/autodl-setup/download
Follow the on screen instructions and input as needed.