In this case I am testing slowing down traffic to 173.192.57.100 for http and https traffic.
sudo ipfw add pipe 1 ip from any to 173.192.57.100 out dst-port 443
sudo ipfw add pipe 1 ip from any to 173.192.57.100 out dst-port 80
Apply a bandwidth restriction of 10KB/sec on the pipe assocated with the previously listed rules.