timezones to own config file

I'd like to know what exactly is to be done for this TODO-item

o Allow customization of the known set of TZ names (generalize the
present australian_timezones hack)

The most recent mail in the archives about this subject seems to be:

http://archives.postgresql.org/pgsql-general/2006-04/msg00966.php

So we'd need a file specifying time zone abbreviations and their offsets, so
for example a file containing lines like:

XST -3.25 # comment here for Xtended Standard Time

The default file would contain the now hardwired values from datetime.c.
Postmaster would parse the file at least on startup or during SIGHUP as well
and (after a few checks) merge the list with the remaining values from
datetime.c (keeping them ordered alphabetically).

I wondered especially if there was a need to associate the abbreviation in
some way to the entries from the zic database but datetime.c seems to just
add or subtract the offset and save the resulting time without further time
zone information.

Thanks,
Joachim