usually in your torrent client options/preferences pages
there is connection tab
select that, then u get the page to set up connection type, proxy ip and port.
click apply/ok after done
example in utorrent : preferences >> connections >> select type (http/https/socks) >> proxy >> port >> press ok/done
i think thats what u meant by ur question
what im interested to know if there is any softwares that u can put in loads of proxies, and it will simulates a download so u can get into the top downloaded section. just a thought.