CakePHP switch database (using same datasource) on the fly?

Made it work using this (create a new connection on the fly) :

$newDbConfig = $this->dbConnect($serverConfig);
$this->Model->useDbConfig = $newDbConfig['name'];
$this->Model->cacheQueries = false;

With :

/**
 * Connects to specified database
 *
 * @param array $config Server config to use {datasource:?, database:?}
 * @return array db->config on success, false on failure
 * @access public
 */
function dbConnect($config = array()) {
    ClassRegistry::init('ConnectionManager');

    $nds = $config['datasource'] . '_' . $config['database'];
    $db =& ConnectionManager::getDataSource($config['datasource']);
    $db->setConfig(array('name' => $nds, 'database' => $config['database'], 'persistent' => false));
    if($ds = ConnectionManager::create($nds, $db->config)) return $db->config;
    return false;

}