query_posts post_parent Want Page Descendants

I’m trying to use query_posts to list all descendants of a page ID. Using post_parent only lists the first-level children.

This Trac ticket seems to address it: http://core.trac.wordpress.org/ticket/5742, but I don’t understand it — post_parent only lists the first-level children.

Here’s my code: http://pastebin.com/b6aw9qMN

How do I get query_posts to list all descendants of a page ID?