Subject:   -21- How can I change clogin's background to an image?
Date: 05 Nov 1995 00:00:01 EST

  Convert the image to xbm ("X BitMap") format. (See under "IMAGE FILES"
  below for conversion programs.) Uncomment the 'xsetroot' line in
  /usr/lib/X11/xdm/Xlogin and change the filename after '-bitmap' to
  your .xbm file. If your image is smaller than your screen, it will be
  tiled to fill the screen.