I've done this. Just edit wp-filebase\classes\TplLib.php file and comment out the remove action. ;)
// remove existing onclicks
// $tpl = preg_replace(array('/<a\s+([^>]*)onclick=".+?"\s+([^>]*)href="%file_url%"/i', '/<a\s+([^>]*)href="%file_url%"\s+([^>]*)onclick=".+?"/i'), '<a href="%file_url%" $1$2', $tpl);Then you can add onclick functions to the template.
