Let's say you need to backport a fix from one BitKeeper repository to another. Here's one way to do it. I suppose there are other or better ways to apply a patch, especially if you have a lot of changesets to backport. But if you're limited to a few changesetd, this seems to work for me.
The following documentation is useful :
http://www.bitkeeper.com/Documentation.FAQS.Linux.html
1. Create personal clone of target repository :
$ pwd /usr/me $ mkdir target $ cd target $ bk clone /share/source/code code