I am using the Wordpress theme Mesozoic and I want to put a link to the zenphoto index of albums in the navigation section in the sidebar.

That section gets created by a call to wp_list_pages.php.

Is the only way to do this by hacking the wp_list_pages.php file?

Is there a way of creating a page in WP that automatically executes the ZP index.php file ?

May I suggest the Page Links To plugin for WordPress? I use it on my site to do the exact same thing you are trying to do. Checkout the Gallery link in my Pages list (it makes use of this plugin).

Thank you - exactly what I needed !