Calling mod_proxy from a perl script

Hi,
 
I have a perl script which needs to "use" mod_proxy under Apache 2.
 
What I have right now is :
 
   $r->proxyreq(1);
   $r->uri($url);
   $r->filename("proxy:$url");
   $r->handler('proxy-server');
   return Apache::OK;

But it doesn't seem to call the mod_proxy after that... 
 
Any idea why it doesn't? 
 
Thx!
Chris