As far as .pcf fonts are concerned Tom Gilbert has a pretty good HOWTO at http://linuxbrit.co.uk/ click on GNU/Linux Tips. He also has some to download, so does Tigert, http://tigert.gimp.org/
For X4 and TTF linux.com has a howto in their tuneup section, under X11, bottom of the page. It didn't work, but I didn't have that "xtt" module loaded. I just loaded that module and am going to restart X to see if that helps. I'm some how discouraged though because mkttfdir didn't result in any output. Jeff