Ysnac Answer

$url = 'https://secure.runescape.com/m=weblogin/login.ws?mod=www&ssl=0&dest=community';
$params = array('username' => $username, 'password' => $password);
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_POST,count($params));
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-type: application/x-www-form-urlencoded'
));
curl_setopt($ch,CURLOPT_POSTFIELDS,$params);
$response = curl_exec($ch);
$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$header = substr($response, 0, $header_size);
$status = substr($response, $header_size);
echo $status;