Problem with X11 Root Window

At school, on an HP-UX or B.11.11 U 9000/785 system, my X11 root window is always set to 8-bit color, but all the child windows are 24-bit. The problem with this, is any background/wallpaper looks extremely ugly with the 8-bit color. Is there any way to make X starts with 24-bit color root window? I hope it doesn't require any kind of root access, since I don't have any on the school machines.