Zend_Oauth_Consumer でプロキシサーバを経由する方法

$config = array(
    'siteUrl'        => 'http://example.com/oauth',
    'consumerKey'    => 'xxxxx',
    'consumerSecret' => 'xxxxx',
    'callbackUrl'    => 'http://example.com/callback',
    'authorizeUrl'   => 'https://example.com/oauth/authorize',
);

$client = new Zend_Http_Client(null, array(
    'adapter'    => 'Zend_Http_Client_Adapter_Proxy',
    'proxy_host' => 'proxyサーバのホスト名',
    'proxy_port' => proxyサーバのポート番号,
));

$consumer = new Zend_Oauth_Consumer($config);
$consumer->setHttpClient($client);