Editing HTTP Headers

Hi,
I am trying to write an Internet privacy program. What I'm having trouble with is editing HTTP headers before they leave the system.

I need to change items such as the referer and o/s to a different value.

Like the InterMute program.

Anyone got Ideas

Applications that strip that kind of information are typically web proxies. Your browser would ask your proxy program for a web page, it would then go out and get the data sans all the header tags.