自分のタイムラインだけのTwitter投稿画面改

<?php

//ポスト
if(isset($_POST['status'])){
	$status = trim($_POST['status']);
	$rss = simplexml_load_file($rssurl);
	if($status != "" && $rss->channel->item[0]->description != $username.": ".$status){
		$url = "http://twitter.com/statuses/update.xml?";
		$params = "status=". rawurlencode($status);
		$result = file_get_contents($url.$params , false, stream_context_create(array(
			"http" => array(
				"method" => "POST",
				"header" => "Authorization: Basic ". base64_encode($username. ":". $password)
			)
		)));
		usleep(500000);
	}
	header("Location: ".$base_url);
	exit;
}

?><html><head><title>post</title></head><body><form action="./" method="POST"><textarea name="status" cols="50" rows="4" wrap="soft"></textarea><input type="submit" name="write" value="up"></form><div><?php

//タイムライン表示
$rss = simplexml_load_file($rssurl);
$date = "";
for($i = 0; $i < 20; $i++) {
	$pubDate = strtotime($rss->channel->item[$i]->pubDate);
	if($date != date("Ymd",$pubDate)){
		$date = date("Ymd",$pubDate);
		echo $date."<br>";
	}
	echo date("H:i:s : ",$pubDate);
	echo str_replace($search,$replace,$rss->channel->item[$i]->description)."<br>";
}
?></div></body></html>

$username $password $rssurl $base_url $search $replace は各自何とか
$rssurlはuser_timelineじゃないとアレ