What you are looking for is called a proxy. It can be a real pain to do because only so many free proxies exist. Depending on how many files you want to load, it can be more of a pain to do. I prefer to switch proxies manually. You can try web based proxies and see if they work.
http://proxy.org/cgi_proxies.shtml is a list of some free ones. But be careful since they have a tendency of loading lots of ads.