``This article offers a brief (but detailed) explanation of how to use 
pkg_comp to build packages under NetBSD in a chroot sandbox, without 
affecting already installed packages. In other words, you can build stuff 
without killing everything that depends on it while it builds ;-)''

URL: http://www.bsdfreak.org/modules/news/article.php?storyid=1

-- 
NetBSD - Free AND Open!      (And of course secure, portable, yadda yadda)