Dave Dash has posted guide to setting up a PHP installation that can work with both the Symfony framework and the doctrine functionality on a Dreamhost server.
Lately I've been experimenting with Doctrine on a few projects. It does have some requirements, including the PDO layer of PHP 5.2. Things didn't work right off the bat on Dreamhost (which I still use for non-critical things), so I opted to build my own php.
The post is basically a cut and paste of a handy "install all" script you can customize to match your installation preferences.