[faq Q] Where is FAQ on getting X after install

[Harry Putnam <reader_(_at_)_newsguy_(_dot_)_com>]

This will sound pretty lame... sorry:

I've found information in the faq a few weeks ago that describes how
to get the XFree pkgs after having installed without them.

Easy enough and general info can be found under: [...] Installation
guide => 4:10 Adding a file set after install

However I recall something specifically about X that mentioned some
small config that needed to be turned on if you installed X stuff
after the fact.

Today, looking for about 1/2 hour thru the faq, I'm not finding that
section .... can someone lead the blind here?