[Plugin: Posts 2 Posts] Order main query using connected item title

I’d like to be able to sequence the results for a custom post type archive using the title from a connected custom post type.

For example, post types product and manufacturer with a one-to-many connection from manufacturer to product.

On the product archive, I’d like to be able to order them by manufacturer name then by product name.

I don’t want the overhead of doing a main WP Query, then chucking it away generating a new query for manufacturers and using each_connected on that.

What I wondered was whether use each_connected (there’s a couple of examples in this support forum) in the WP_Query with some sort option, or by using the posts_order filter manually. I’d then use pre_get_posts to tweak the main query.

I’m failing at step one though, and can’t get each_connected to fire up from a WP_Query, so doing

$products_with_connection=new WP_Query(array(
	'post_type'=>'product',
	'nopaging'=>true,
	'orderby'=>'name',
	'order'=>'ASC',
	'each_connected' => array(
		'post_type' => 'manufacturer',
		'nopaging' => true
	)
));

makes no difference to the results with/without each connected.

Am I barking up the wrong tree here, and how would you achieve the objective?

http://wordpress.org/extend/plugins/posts-to-posts/