Get and replace

OK all you gurus. Here's what i want to do. I want to get data from http::header "X-Forwarded-For" and replace the data in client_addr with what I get from X-Forwarded-For. I need to grab th IP found in X-Forwarded-For and put it in the client_addr so that I can pass it to my ISA servers. Any ideas?

 

 

Thanks,

 

Scott