Just a few things about the HOW-TO:
Since you already have the suggestion of using CPAN for
XML:Twig just have them pull down XML::Writer for XMLTV
while they are at it.
Put the Instructions for XMLTV and the listing.pl file
further down the page, preferably AFTER setup of the
php stuff. Once the access to MYSQL and APACHE and PHP
are working then describe the why to LOAD the channels
and programs ( I spent hours after I ran setup.pl
messing around with listings.pl and would like to have
seen the site before I actually was committed to XMLTV.)
Lastly as you mention, xawtv is not required for this
system. Actually only xawtv-control is need for actual
channel changing (and volume and norm etc.)
I would mention that if they have had no experience
with capture cards (as I was) xawtv is a good place to
start to make sure they have all the drivers and
options set correctly.
Just some ideas.