Find:
-----------
$posts=$DB_site->query("SELECT post.dateline as dateline,post.postid as postid,post.pagetext as pagetext,
                               post.allowsmilie as allowsmilie,post.signature AS showsignature,post.title as title,
                               post.ipaddress as ipaddress,post.iconid as iconid,post.username as fakename,
                               post.userid as userid, 
                               user.userid as userid,user.email as email,user.username as username,
                               user.usertitle as usertitle,user.signature as signature,user.showemail as showemail,
                               user.homepage as homepage,user.icq as icq,user.aim as aim,user.yahoo as yahoo,
                               user.joindate as joindate,user.posts as posts 
                        FROM post 
                        LEFT JOIN user ON (user.userid = post.userid) 
                        WHERE post.threadid=$threadid AND visible=1 
                        ORDER BY dateline $postorder
                        LIMIT $limitlower,$perpage");
-----------

Add to the end of the select portion:
-----------
,user.biography as biography
-----------

Find:
-----------
$userinfo=$post;
-----------

Under it, add:
------------
    $bio = split("\n", trim($userinfo[biography]));
    $location = "";
    $interests = "";
    while(list($key,$val)=each($bio)) {
    	if (strlen(strpos($val, 'Location:'))) {
    		$location = eregi_replace("^Location:([^\\[]*)", "\\1", "$val");
    	} elseif (strlen(strpos($val, 'Interests:'))) {
    		$interests = eregi_replace("^Interests:([^\\[]*)", "\\1", "$val");
    	}
    }
    if ($location) { $location = "Location: $location"; }
    if ($interests) { $interests = "Interests: $interests"; }
------------

Then reference $location and/or $interests in the postbit template.