Move to core xml from contrib/xml2

Hi,

we have encountered huge memory problems (segfault on 8.4.2, out of
memory on 8.4.3) with our xml functions when moving from 8.3 to 8.4, as
mentioned here:
http://archives.postgresql.org/pgsql-general/2010-03/msg00563.php

We think about moving from contrib/xml2 to the core xml support.
But i have no clue how to change the database functions so they use the
core xml support. I have already uninstalled contrib/xml2, but now i
dont know further. I seem to cannot find any information how to use the
core xml support in the manuals or anywhere in the net.

Thanks in advice,

Frank Jansen