Lighttpd

Hi,
I using x-sendfile (lighttpd 1.5) and I trying to count file downloads (only who 100% downloaded) but look like that is not possible, maybe somebody can create patch for this or maybe somebody already know solution???
Will be good if possible to execute some php script when download is 100% finished (additional header for that) and on that way I can count downloads...

I hope that somebody can help...I know that many other people need this solution...

Thanks.