Simple as eat an apple =)
$ sudo apt-get build-dep openssh-server
$ sudo aptitude install fakeroot
after installing all these packages. Download sources of openssh. at the bottom of the page, something like openssh_5.1p1-2.dsc, openssh_5.1p1.orig.tar.gz, openssh_5.1p1-2.diff.gz.
Next... RTFM =). And you are done! Have fun!
