Badndwidth/Download Limit w/ PHP

Hello,

I'd like to make some download speed limitation on some of my files
using PHP. I know that an Apache module can do that, but i cannot access
my ISP Apache configuration.

My idea was to put the file into a .htaccess protected diretory and to
build a "proxy" with PHP.

I can also put a download limit (after n download per day the script
deny download). Any idea or known script doing that?

Thank you in advance,

Nicolas