Sometimes when I'm downloading free and open source software via bit-torrent I like to hide who I am to mix things up a bit. It's probably more secure too. How does one do that? I can't imagine it's easy.
Tor is not created for routing large amounts of data.
Now hiding your IP while downloading free software is generally speaking a good idea. There are a lot of organizations out there monitoring the sharers of software that is free to distribute by license. Also we have a long list of people that are charged and convicted for sharing free open source software.
What you need is VPN service that allows sharing of free open source over its network and taking your privacy seriously. The things that you want to look for are no logs, and location in a country other than the one you are resident of. In case some authorities have interest of your sharing of the last debian iso files, they will have much harder time subpoenaing the VPN provider and using the latest techniques of rubber hose cryptoanalysis on your traffic.
A good resource for the providers is that torrentfreak article
With a VPN provider you will be ensured that your efforts of obtaining and distributing free open source software will be free from interference of external forces.
You cannot hide your IP address from everyone... as soon as you are downloading a piece of data from someone, that someone will be able to find out who you are, because the IP address is what they need to be able to send you the data (it's your 'address' on the internet).
As a direct result, you can try to hide your 'identity' from specific people or organisations, but there is never going to be any guarantees that you may not have the misfortune of connecting to them directly, at which point the torrent software will provide them with your address for the data to be sent to.
There are a number of tools that try to 'hide' from copyright organisations by using a blacklist of IP addresses that the software will not be allowed to ask data from. Note that this is not a foolproof solution, because it is only as good as the blacklist is (and as soon as they register a new IP address, it's not perfect any more).
Other solutions involve anonymising software, or new torrent protocols that use encryption and passing data along multiple people in a network. These are typically collaborative tools where you have to do some of the passing along for others to be allowed to use them for the same. This slows downloads down tremendously, and ultimately someone has to connect to the actual source of the data, which may be the person you are hiding from, and it could be you doing the connecting for someone else... this is again not fool-proof.
As you can see, there exist no perfect solutions, because in all cases at some point somebody has to talk to the person that has the data, and at that point they must expose their IP to that person.
If you are this worried about hiding, then really... don't download things you want to keep secret. "Just say No"
PeerGuardian 2 doesn't exactly "hide" your IP, but this does blacklist known government agencies, snoopers, spoofers, etc. while you are using P2P torrents. It should offer the protection you're looking for.