Open printthread.php, change query on line 126 to:
PHP Code:
$posts = $DB_site->query("
SELECT post.*,post.username AS postusername,user.username,userfield.*
FROM " . TABLE_PREFIX . "post AS post
LEFT JOIN " . TABLE_PREFIX . "user AS user ON(user.userid = post.userid)
LEFT JOIN " . TABLE_PREFIX . "userfield AS userfield ON(user.userid = userfield.userid)
LEFT JOIN " . TABLE_PREFIX . "deletionlog AS deletionlog ON(deletionlog.primaryid = post.postid AND type = 'post')
WHERE post.threadid=$threadid AND post.visible=1 AND deletionlog.primaryid IS NULL
ORDER BY dateline $postorder
LIMIT $startat, $perpage
");
Then add the fields as normal to the template.