If you meant the GNU/Linux version of Pacho's modified client the links are all currently down, but I'll link the URL below for reference. The two methods I know to work on Linux are installing javaws, and running 'javaws -nosecurity autohaven.jnlp', I found some interface lag with this method but it was stable. Personally I am using the Windows version of Pacho's client through WINE. There were some issues with the ui elements on the setup menu only being interactable in the very top left corners, but when inside the game its worked well.
viewtopic.php?f=5&t=2965 is Pacho's topic about the client.