WP-dTree and WP-ecommerce

I’m trying to set up a store that has TONS of categories and subcategories. There doesnt seem to be a great way to display lots of cats and sub cats in wp-ecommerce. how hard would it be to use WP-dTree with wp-ecommerce’s product groups? they use <?php show_cats_brands(); ?> to list categories. im at a loss for a decent way to list this without it being a mile long.