Add this to routes.php.

// Needed to support sitemap.xml and sitemap.xml.gz
// should be improved :)
'sitemap.xml|sitemap.xml.gz|robots.txt' => 'sitemap/index',

Controller:

<?php

\Package::load('sitemap');

class Controller_Sitemap extends \Sitemap\Controller {

    protected function _sitemap()
    {
        $result = \DB::select('url', 'updated_at')
            ->from('profiles')
            ->where('completed_step', 3)
            ->where('status', '<', 2)
            ->where('active', '<', 2)
            ->order_by('id', 'desc')
            ->execute()->as_array();

        foreach ($result as $k => $r)
        {
            $result[$k]['url'] = \Uri::base().$r['url'];
        }

        return $result;
    }

    protected function _robots()
    {
        return 'controller robots.txt';
    }

}