Installing BackTrack 4 R1 to a USB Flash @ TechwareLabs
Quote: "In this tutorial you will learn how to install the latest version of BackTrack (BackTrack 4 R1) to your USB flash drive. Not only will you be able to boot BackTrack off of a flash drive, but it will also allow you to have persistent changes. This tutorial will also work for previous versions of BackTrack."
Read the review here