The following works on several blogs 1.2.1 and 1.2.2.
Edit your wp-trackback.php file.
Search for :
("$comment_post_ID", "$author", "$email", "$tb_url", "$user_ip", "$now", "$now_gmt", "$comment", "$approved") and change the $approved to 0 (zero). This will force all trackbacks into moderation.
This will not moderate comments. It will cause ALL trackbacks to be thrown into moderation for approval.
To disable trackbacks completely you can comment out the following line :
$pingstatus = $wpdb->get_var("SELECT ping_status FROM $tableposts WHERE ID = $tb_id"); by putting at the begining of the line \\
then put a new line underneath with :
$pingstatus = 'closed';
This will not disable comments. It will cause ALL trackbacks to be ignored.