Try copying the cat tabs call from tpl_header.php to tpl_main_page.php.
PHP Code:
<!--bof-optional categories tabs navigation display-->
<?php require($template->get_template_dir('tpl_modules_categories_tabs.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_modules_categories_tabs.php'); ?>
<!--eof-optional categories tabs navigation display-->
Paste it in where you want it, probably just above
PHP Code:
<?php
/**
* prepares and displays footer output
*
*/
I did something like this with the logo display and it worked fine.
You will need to comment out the code in tpl_header.php.