'always_load' => array('packages' => array(
	'twitter',
	...

Package::load('twitter');

<?php

class Controller_Twitter extends Controller
{

	public function action_signin()
	{
		Session::delete('twitter');
		
		$twitter = Twitter::forge('oauth');
		
		$request_token = $twitter->get_request_token();
		Session::set('twitter.request_token', $request_token);
		
		$url = $twitter->get_authorize_url($request_token['oauth_token']);
		Response::redirect($url);
	}
	
	public function action_callback()
	{
		$request_token = Session::get('twitter.request_token');
		Session::delete('twitter');
		
		$twitter = Twitter::forge('oauth');
		
		$access_token = $twitter->get_access_token(
			$request_token['oauth_token'],
			$request_token['oauth_token_secret'],
			Input::get('oauth_verifier'));
			
		// $access_token has user_id, screen_name, oauth_token and oauth_token_secret
		Debug::dump($access_token);
	}
	
}

	$twitter = Twitter::forge('default', array(
		'user_token'  => 'xxxxxxxxxx',
		'user_secret' => 'yyyyyyyyyy',
	));
	
	$response = $twitter->post('1.1/statuses/update', array('status' => 'Hello!'));
	Debug::dump($response);