What would be the main goals of this installer? Could you elaborate a high level description of it? As I said in the past, beside some annoying deps, anaconda already works for Sabayon and working on a pure Gentoo module would be quite easy. In change you get one of the most reliable graphical installer out there. Text frontend comes for free, but nowadays, there aren't many servers without a vesa-compatible video card or VNC/X-over-ssh/whatever availability.
Regards, -- Fabio Erculiani http://lxnay.com