Pretty simple. When you set up your menu items, choose 'Category Layout' as the 'Menu item type', set 'Parent Item' to 'Menu Item Root' for each of your VM2 categories and finally select the VM2 category in the 'Required Settings' dropdown list. Also, you have to enable SEF Urls in Joomla and VM2 of course. (I don't know if this works with the GA menu, too)