I have used XPF on my 8500 to install X and i could not get it installed until the latest version (2.2.2) that he has released. I also have a 6400 and 6500(my parents machines) that i want to put X on as soon as he does have support for those machines. Sorry i was not on this site sooner to give you a couple of suggestions and to warn you that the 6400 is not supported, but thanks for answering my curiousity of what would happen if i tried. Have you tried to use XPF to install just darwin and not the entire X package? the reason i say this is because if your display is broken then you will be just remotely using it anyways and dont need the GUI part on the system. You could also run like yellow dog linux on it or something of that nature. In alot of ways it is similar, alot of ways it is not though. It would make a great server with YDL on it though.
jeffo