[development] create book via drupal_execute

I'm trying to import content from a number of files into Drupal book nodes. I'm importing a large outline into a D6 site. node_import module does not work for D6 so I've written my own code. I'm able to create the book nodes via drupal_execute, but for the life of me I cannot figure out how to make one page the child of another page. The best I can do is create siblings within a single book. Does anyone have the know-how of the book module or drupal_execute to tell me how to do this? If so please reply to http://drupal.org/node/344040 Thanks, -Dave