Procedure for duplicating WPMU install?

I have WPMU 2.8 installed in a production environment and want to duplicate the installation to a dev location to test upgrading to WPMU 2.9 and then to WP 3.0.1

What would be the correct course of action to do this to achieve a duplicate working copy at dev.example.com seeing as how so much of the original location is hard set in hundreds of instances in the database rather than using a variable?