XSD to Postgresql SQL

I have a big and complicated XML Schema (1.0, W3C standard XSD), which I'd
like use to generate schema for a Postgresql database.  I'm not able to
change the XSD, it's a standard in itself, and I believe most previous
mapping has been with Oracle databases.

Are there standard tools for performing such a conversion?  I appreciate
that the SQL generated may not be unique and it may require some manual
tweaking.

I've looked briefly at Torque, which seems to use its own schema for DB
description, and at Castor, which seems complicated and requires me to go
through JDO and java source code generation -- perhaps I'll have to do that
anyway for the programmatic aspects.  My current methods of population and
retrieval for similar databases use Perl and the DBI/DBD::Pg.

Any pointers would be appreciated, and please tell me if I'm asking the
wrong question or missing the point of Castor or Torque!

Thanks

Julian Scarfe