Pendrivelinux posted a tutorial about running Gentoo Linux from a USB device using Windows.
>> USB Gentoo 2007.0 install
In the following USB Gentoo tutorial will cover how to install, boot and run Gentoo 2007.0 from a USB device using Windows. Gentoo is a popular Linux version named after the Gentoo Penguin. Gentoo was originally created by Daniel Robbins with a goal to create a smaller portable Linux distribution that only included required programs. This Gentoo USB installation tutorial was developed per the request and with a little help from Brendan Jocson, a Pendrivelinux.com subscriber. Kudo's to Brendan!
>> USB Gentoo 2007.0 install