bind applications to ports

Hi,

I use Debian sarge with iptables v1.2.9. What I'm
trying to do is to bind the ports 6882-6889 to my
bittorrent programm called btdownloadcurses in order
to increase the download rate.
In google I figured out that these ports must be
mapped to the application using iptables rules.
Unfortunately, I could find any information
how this rule must look like.

Could you give me a hint.

Are the iptables rules the only changes I have to
do or are further steps required to have bittorrent
working with the aforementioned ports?

Thank you for your answer.

Regards,

Christian