Hi Erv,
That post you link to was from an older version of ULX.
Though Source/Gmod still use a cfg folder, we separated our ULX configuration files away from it.
ULX configuration files are now stored in addons/ulx/data/ulx, copy any files there to your <gmod root>/data/ulx folder, then edit.
Don't edit the actual files in /addons/ulx/data/ulx...remember, addons are virtual, we try to keep ULX from having to have edits there (and can actually break stuff)
I know, I know..some addons have you edit those files.
May want to google about creating your gmod/cfg folder if you don't have one.
Many config files can be stored there, and used to run at startup of server, or while running the server, to store various console commands.(not related to ULX)