<?
$request = array(
'http' => array(
    'method' => 'POST',
    'content' => http_build_query(array(
        'Item' => 'Value',
        'Item2' => 'Value2'
    )),
)
);

$context = stream_context_create($request);

$html = file_get_html('http://www.google.com', false, $context);
?>