2nd header img with alternate menu possible

Hi,

I recently switched from theme twentyten to enlightenment, but now facing the problem how to modify the header for an internal section.
With twentyten it was enough to simply call the alternate image instead of <?php header_image(); ?> and manually extend the wp_nav_menu Parameters with the ID of the private menu instead of the public one…

But with enlightement, it seems I need to modify the custom functions of theme enlightenment, enlightenment_header(), but where do I find it, or is there a better way?