Hi Zach,
The patch looks great. Do I understand correctly that one uses the SQL commands to actually enable listening or send something?
As for where the docs go, I'd say somewhere near the bottom of cl-postgresl.html, with a short mention and a link somewhere in postmodern.html. If you write out a rough draft and submit a patch containing that, I'll be happy to polish up the HTML and such.
Cheers, Marijn