Unfortunately, if you are using Propel 1.4 (Symfony 1.4), it seems that you will have to switch to raw SQL there...
No answer in the (old) Symfony forum : http://oldforum.symfony-project.org/index.php/m/90447/
However, since Propel 1.5 it should work with the new syntax (Doctrine style). It's not detailed in Propel doc but when I test this, it works (gives ORDER BY author.name ASC, author.id DESC
).
$authors = AuthorQuery::create()
->orderByName()
->orderById('desc')
->find();
Maybe consider upgrading to Propel 1.5.