[GameWizard]

Here is all the information that you need: (most if is based on your plugin already)

I have a custom template which appears in inside my profile page, which includes the following code:
$userinfo[field20] and $userinfo[field31] (and a few others, but for the sake of the example I will include these two)

Plugin Name: Init BBCode-Parser
Location: member_start

require_once(DIR . '/includes/class_bbcode.php');
$parser =& new vB_BbCodeParser($vbulletin, fetch_tag_list());

Plugin Name: Parse BBCode in custom profile fields
Location: member_complete

$userinfo['field20'] = $parser->do_parse($userinfo['field20'], 1, 0, 1, 0, 1, 0); 
$userinfo['field31'] = $parser->do_parse($userinfo['field31'], 1, 0, 1, 0, 1, 0);

Here I have all the custom profile fields I want parsed. I can add as many as I want.

The numbers refer to different things, here they are in order:
$do_html, $do_smilies, $do_bbcode, $do_imgcode, $do_nl2br, $cachable