1) Are you SURE the documentation isn't there? Try "man Xorg" and "man Xserver"
2) Did you bother to do an "ls" in the /usr/X11/bin dir? You should check there with "ls X*" and "ls x*" to see what commands start with an X and an x respectively. I bet you find a command that looks like it makes the config for you if you look hard enough.
3) This isn't a "Slackware" issue so much as an X issue. The ONLY way you aren't going to be forced to mess with Xorg or be forced to install XFree86 instead of / along with it is to do LFS, or go back to an older distro. All of the major distros have moved to Xorg due to licensing issues with XFree86
4) You have your homework (1 and 2 above) so go do it... don't procrastinate... and come tell us what you learned!
and long time no see Omo... welcome back