Launching a WP script via Linux cron

I want to be able to launch a script in one of my plug-ins from the Linux cron. Linux' cron gives me a lot more granular control over cron activities than the internal WP cron.

I know I can call wget with a URL to my php file, and I'm guessing I need to include wp-config.php to load most of the WP environment, but what do I really need to include, load, and set to get the WordPress environment loaded in advance of running my script?