menu.phpの<body>直下に以下のソースを追加。

$proxy_php = $prefdir."/p2_proxy.php";

if($_POST['proxyhost']){$proxyhost = $_POST['proxyhost'];}
if($_POST['proxyport']){$proxyport = $_POST['proxyport'];}
if($_POST['proxyuse']){$proxyuse = $_POST['proxyuse'];}
if(get_magic_quotes_gpc()) {
$proxyhost = stripslashes($proxyhost);
$proxyport = stripslashes($proxyport);
}

if( isset($_POST['proxyhost']) && isset($_POST['proxyport']) ){

if (isset($_POST['proxyuse'])) {
$proxyuse = $_POST['proxyuse'];
} else {
$proxyuse = 0;
}

$proxy_cont =<<<EOP
<?php
\$proxyuse='{$proxyuse}';
\$proxyhost='{$proxyhost}';
\$proxyport='{$proxyport}';
?>
EOP;
FileCtl::make_datafile($proxy_php, $pass_perm);
$fp = @fopen($proxy_php,"w") or die("p2 Error: PROXYを更新できませんでした");
fputs($fp, $proxy_cont);
fclose($fp);

}

if($doctype){ echo $doctype;}

if($proxyuse){
$proxyuse_checked=" checked=\"true\"";
}

echo <<<EOFORM
<form id="login_with_id" method="POST" action="{$_SERVER['PHP_SELF']}" target="_self">
{$k_input_ht}
PROXY: <br><input type="text" name="proxyhost" value="{$proxyhost}" size="20"><br>
PORT: <input type="text" name="proxyport" value="{$proxyport}" size="5"><br>
<input type="checkbox" name="proxyuse" value="1"{$proxyuse_checked}>外部PROXY使用<br>
<input type="submit" name="submit" value="設定">
</form>\n
EOFORM;