Try Daniel Stone's 4.3 XFree packages (www.penguinppc.org/~daniels) (and let us know)
Ok, I did xserver-xfree86 seems to install but debconf complains about all the "_description:" stanzas in the templates file. It looks as though they should be "Description:" instead. I checked the i386 package and the _description stanzas are there too.
Too bad I don't know how to unpack all the files in the deb file, modify one and then pack them again without building the package. And getting the source packages would take forever (I'm behind a slow link now).
Eduardo.