If UltraSurf works by using non-transparent proxies, then I suppose you could use that, so long as it changes it at the IP Stack and not just for browsers (basically you have to be sure it works for other applications). Some proxies will throttle bandwidth through them, so that they don't have to incur high bandwidth charges. So I haven't used it, so I'm not sure how they usually works with the proxies that it captures.
Software like PeerGuardian advertise blocking IP's that may be from copyright holders and their agents, however, it blocks a lot of legit IP's as well and from my perspective they just do simple ARNIC, etc. searches and then block the entire IP block, which is almost useless and broad.
Anyway, the only safe ways otherwise is to use an anonymous VPN service or a SeedBox (neither are free, but they usually offer group logins and PayPal-type donations from an entire group to pay the bill).
Anyway, the best things to do is A) Encrypt your torrent traffic B) Use only private trackers C) Don't seed a lot (I know it goes against torrent philosophy, but so does pirating) D) Don't max out your upload (doing so hurts your download rate anyway), but find some sort of happy medium.
And of course, have the decency to be on your own ISP service if you are going to pirate and don't screw your parents or someone else over.