I'm sorry, I got impatient and went ahead and did it. I'm posting what I did here for other users:
/template/html/mod_easyblogcategories/default.php
<?php
/**
* @package EasyBlog
* @copyright Copyright (C) 2010 Stack Ideas Private Limited. All rights reserved.
* @license GNU/GPL, see LICENSE.php
*
* EasyBlog is free software. This version may have been modified pursuant
* to the GNU General Public License, and as distributed it includes or
* is derivative of works licensed under the GNU General Public License or
* other free or open source software licenses.
* See COPYRIGHT.php for copyright notices and details.
*/
defined('_JEXEC') or die('Restricted access');
?>
<script type="text/javascript">
function redirectMe( element )
{
window.location.href= element.value;
}
</script>
<div id="ezblog-categories" class="ezb-mod mod_easyblogcategories<?php echo $params->get( 'moduleclass_sfx' ) ?>">
<?php if(!empty($categories)){ ?>
<select name="eblog-category" onchange="redirectMe( this );">
<?php echo modEasyBlogCategoriesHelper::accessNestedCategories( $categories , $selected , $params ); ?>
</select>
<?php } else { ?>
<?php echo JText::_('MOD_EASYBLOGCATEGORIES_NO_CATEGORY'); ?>
<?php } ?>
</div>
/template/html/mod_easyblogcategories/item.php
<?php
/**
* @package EasyBlog
* @copyright Copyright (C) 2010 Stack Ideas Private Limited. All rights reserved.
* @license GNU/GPL, see LICENSE.php
*
* EasyBlog is free software. This version may have been modified pursuant
* to the GNU General Public License, and as distributed it includes or
* is derivative of works licensed under the GNU General Public License or
* other free or open source software licenses.
* See COPYRIGHT.php for copyright notices and details.
*/
// no direct access
defined('_JEXEC') or die('Restricted access'); ?>
<option value="<?php echo EasyBlogRouter::_('index.php?option=com_easyblog&view=categories&layout=listings&id='.$category->id . $menuItemId );?>"><?php echo JText::_( $category->title ); ?></option>