any way for ORDER BY x to imply NULLS FIRST in 8.3?

Is there any way to "hardcode" the NULL handling in an index (as per
http://www.postgresql.org/docs/8.3/static/indexes-ordering.html) so that
SELECT * FROM t ORDER BY foo automatically implies NULLS FIRST (and,
similarly so that SELECT * FROM t ORDER BY foo DESC automatically
implies NULLS LAST)? Thing is, I'm using PHP Symfony/Propel to generate
their SQL and have no easy way to influence how they do so.

Thanks.