HOWTO Build a Gentoo LiveCD

"This article will explain to you, how you can build a Gentoo (http://www.gentoo.org/) LiveCD with Catalyst (http://www.gentoo.org/proj/en/releng/catalyst/). Catalyst is a tool which allows you easily to maintain a set of profiles for your favorite stages or LiveCDs. This HOWTO will give you hints, tips, and tricks to build your own version of a Gentoo Linux LiveCD. If this is your first time building a LiveCD using Catalyst, keep reading. Otherwise, advance to the end for customization help."

http://gentoo-wiki.com/HOWTO_build_a_LiveCD