documentation? debug mode?

Hi,

I'm trying to use the Layout directive and it just plain doesn't do 
anything. It works fine if I use LayoutFooter and LayoutHeader, but I 
want to use Layout to insert some ad code after a specific tag.

I've so far been unable to find any documentation other than the really 
old stuff here: http://docs.tangent.org/mod_layout/faq-3.html , much of 
which is 404, and a mirror of the missing bits here: 
http://www.musc.edu/webserver/directives/ .

Actually, the best documentation I was able to find was the directives.h 
file, which at the very least gives me a slightly newer list of 
directives (but is itself out of date -- it lists the apparently defunct 
LayoutMerge for example).

I'm also confused about how to specify a pattern -- the tag I want to 
match on my pages is <td class="center">, which has a space in it, as 
well as quotes. Do I put single quotes around the whole thing? Do I 
backslash the quotes and the space? What kind of pattern syntax does 
mod_layout expect?

Anyway, that's a moot point, because even when I try much simpler 
patterns (the string "replaceme"), the Layout directive has no effect 
whatsoever. I tried compiling with DEBUG defined, but I can't figure out 
where those debug messages are supposed to be output -- and yes, I tried 
running apache with loglevel debug; nothing.

The directive that I'm trying to use is:

Layout "replaceme" "test" append

Help?

(Apache 2.2.4, then tried upgrading to 2.2.8)

~Felix.