Accessing menu_primary_local_tasks() in template.php

I want to change the display of tabbed menu items to block images and text (like in aquasoft theme).

As such I wanted to access the menu_primary_local_tasks() function (which lives in includes/menu.inc) within template.php, then to walk through the array and make the changes.

How can I get access to that function in template.php?

I noticed that the aquasoft developers were able to access menu_primary_links() in there with no "include_once" or other visible means of connection.

I'm still trying to get my mind around the parts in themes and where they should live. When I figure it out I think I will make a graphic image representing how all the pieces fit together, it can be quite frustrating. However, as with other parts of Drupal, once the concept is grasped then it makes sense. It is just grasping the concept that is hard.