Query String and custom field sort

Hi,

I am using the query string example form the codex, and it works great.
http://codex.wordpress.org/Displaying_Posts_Using_a_Custom_Select_Query

<?php

	 $querystr = "
	    SELECT wposts.*
	    FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
	    WHERE wposts.ID = wpostmeta.post_id
	    AND wpostmeta.meta_key = 'kids_book'
	    AND wpostmeta.meta_value = 'yes'
	    AND wposts.post_status = 'publish'
	    AND wposts.post_type = 'post'
	    AND wposts.post_date < NOW()
	    ORDER BY wposts.post_date ASC
	 ";

	 $pageposts = $wpdb->get_results($querystr, OBJECT);

	?>

I have another meta key in these posts called ‘book_sort’ I would like the sort order of my posts to be the value of ‘book_sort’

So how do i work something like this:

'meta_key' => 'book_sort',
'orderby' => 'meta_value'

…into the above query string.

Thanks!

Nadine