Can I ask a stupid question?  :)  Why is it so difficult to edit the
MAILTPL file and put it when you need to change the INFO section?  You
should only be storing the parts you actually have edited anyway...
for upgradability's sake, you should never store a MAILTPL section that
you haven't changed.  I'll take a wild stab and say that most list owners
would only store the INFO section and <maybe> the $SIGNUP section, and
leave the rest alone.  If you store the whole thing each time, <none>
of the messages in it get updated if the DEFAULT MAILTPL changes.
 
Seriously, Roger, I'm not being facetious, I just don't understand the
problem.  What I'd do is just keep a copy of the MAILTPL file around so
I could edit it quickly and put it as necessary.  In fact this is what
I do with most of my stored files.
 
Best,
Nathan