You need to edit the modules\boonex\persons\classes\BxPersonsModule.php file and add after those lines:

    return false;

    }

the following:

public function serviceEntityInfoAdv ($iContentId = 0, $sDisplay = false)

    {

// your own code to draw the special fields in the new info block

    }

And call this method in the service block with the following content:

array (

  'module' => 'bx_persons',

  'method' => 'entity_info_adv',

)