check this example it uses a post from a php page
<?php
/**
 * MS-Excel stream handler
 * Excel export example
 * @author      Ignatius Teo            <
[email protected]>
 * @copyright   (C)2004 act28.com       <http://act28.com>
 * @date        21 Oct 2004
 */
require_once "excel.php";
$export_file = "xlsfile://".$_POST['archivo'].".xls";
$fp = fopen($export_file, "wb");
if (!is_resource($fp))
{
    die("Cannot open $export_file");
}
// typically this will be generated/read from a database table
$assoc = array(
    array("Sales Person" => "Sam Jackson", "Q1" => "$3255", "Q2" => "$3167", "Q3" => 3245, "Q4" => 3943),
    array("Sales Person" => "Jim Brown", "Q1" => "$2580", "Q2" => "$2677", "Q3" => 3225, "Q4" => 3410),
    array("Sales Person" => "John Hancock", "Q1" => "$9367", "Q2" => "$9875", "Q3" => 9544, "Q4" => 10255),
);
fwrite($fp,serialize($assoc));
fclose($fp);
header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header ("Last-Modified: " . gmdate("D,d M YH:i:s") . " GMT");
header ("Cache-Control: no-cache, must-revalidate");
header ("Pragma: no-cache");
header ("Content-type: application/x-msexcel");
header ("Content-Disposition: attachment; filename=\"" . basename($export_file) . "\"" );
header ("Content-Description: PHP/INTERBASE Generated Data" );
readfile($export_file);
exit;
?>