Php :: File Download - Set Headers Then Redirect?

I would like to do this, without the "readfile()" part:

header("Content-type: application/force-download");
header("Content-Transfer-Encoding: Binary");
header("Content-length: ".filesize($file));
header("Content-disposition: attachment; filename="".basename($file).""");
readfile("$file");

Basically I am trying to forward a download to another URL but at the same time I need to be able to set headers like "filename".

The readfile($file) function will not do it for me, because the the $file is not stored on the same server as the PHP script (not even the same datacenter) Is this even possible ? If not via PHP, maybe FLASH could do this ?