Do you understand the principal of a torrent? You can't stop it by 'loading it down' with leechers. It is an ambiguous term (see
http://en.wikipedia.org/wiki/Terminology_of_BitTorrent)
Since all connections are peer to peer, there is no webserver to overload, adding in extra peers does nothing. In fact, you would have to download the file yourself (which is illegal), and even then it automatically seeds (leechers can still seed). In fact, you probably won't even get connections unless you are seeding at the same time, which is a method designed to prevent this sort of thing (unless you use a special client).
In essence, by downloading the file, you are also distributing it to other people, which in fact improves the speed of the torrent. Unless you go about attempting the 'ping of death' on some individual ips (also illegal), you will not be able to stop it.
I'll do a little example here (<> means sharing of data both ways)
seeder
<_________>
leecher<>leecher
<>________<>______<>_______<>
leecher<>leecher<>leecher<>leecher
Basically, initially it will slow the torrent down, but as you get more of the file, it will actually speed it up, as there are more download sources (it is co-ordinated so that each of the clients in the 'swarm' downloads different parts of the file, then shares them with each other). Also You can have 99% of the file and still be classed as a leecher, even if you are actually uploading.
I hope that explains everything clearly. Wikipedia is your friend in these instances
