I've been asked to clear up some confusion here. Let's just say that "Gentoo Linux on OSX" is a project that is not active anymore and instead "Gentoo Prefix on OSX [and other operating systems]" has been active.
It is kinda confusing because of the timelines involved. The first attempt was simulating Gentoo/BSD [before my time with the project] but now we have just moved to this concept of an offset prefix installation which works quite well and harnesses the Gentoo Linux developer team. However, this topic is highly diverged from the 3 year old thread here. :)
mattmatteh was generally correct in his post (and a active Gentoo Prefix community memeber, thanks!) except a few terms were mixed up, "gentoo on osx"
: http://www.gentoo.org/proj/en/gentoo-al ... argets.xml