There are several patches for older version of Apache 1.3. I have adapted the patch originaly written by the KAME Project and later by FreeBSD to the version 1.3.42 of Apache httpd server. Also many thanks to Eugene Cookmeyer for submitting a fix in October 2010.
To add IPv6 to Apache 1.3.42 get the apache sources from Apache-Homepage
Add the IPv6-patch with the command
patch -p0 < apache-1.3.42-ipv6.patch
There is also a IPv6 patch for mod_perl written by Marc Balmer