update_with_media.php

<?php
require_once '/path/to/tmhOAuth/tmhOAuth.php';

$obj = new tmhOAuth( array(
  'consumer_key'    => 'consumer_key',
  'consumer_secret' => 'consumer_secret',
  'user_token'      => 'access_token',
  'user_secret'     => 'access_token_secret',
) );

$file = 'test.jpg';
$image = file_get_contents( $file );
$imagesize = getimagesize( $file );

$api_url = 'https://api.twitter.com/1.1/statuses/update_with_media.json';
$params = array(
  'status' => "hey",
  'media[]' => $image . ";type=" . $imagesize['mime'] . ";filename=" . basename( $file ),
);

$code = $obj->request( 'POST', $api_url, $params );
$response = $obj->response['response'];