Adding number of views to topic list

Hi
Need some help.
I want to insert a new column into the topic list table to show Topic views count. Got some code working, but I have a problem with the table headings.
In template_preprocess_forum_topic_list(&$variables) in D6_compat.inc, I see the headings are in the $forum_topic_list_header array. But this array is made in the core forum.module:

$forum_topic_list_header = array(
    array('data' => ' ', 'field' => NULL),
    array('data' => t('Topic'), 'field' => 'n.title'),
    array('data' => t('Replies'), 'field' => 'l.comment_count'),
    array('data' => t('Created'), 'field' => 'n.created'),
    array('data' => t('Last reply'), 'field' => 'l.last_comment_timestamp'),
);

I want to insert another heading into it:

$forum_topic_list_header = array(
    array('data' => ' ', 'field' => NULL),
    array('data' => t('Topic'), 'field' => 'n.title'),
    array('data' => t('Replies'), 'field' => 'l.comment_count'),
    array('data' =>t('Views'), 'field' =>'l.topic_views',   //<<<<insert here
    array('data' => t('Created'), 'field' => 'n.created'),
    array('data' => t('Last reply'), 'field' => 'l.last_comment_timestamp'),
);

How would I do that without having to change code in the core module?