Much easier than unetbootin, and is persistent but takes a while.
I've done this on BT5 through the current Kali version.
The install must be done on a desktop, choose a fast drive if you only
have usb 2. the first step is to disconnect any and all hard drives by
removing just the signal or power cable.
Boot from a good DVD with the USB drive in place.
With no hard drives onboard the installer will only see the USB drive
and will allow it as a selection. This will not happen with internal drives
in place. Begin the install then choose erase and use the entire drive when prompted.
Takes around 1/2 hour. boot times are similar to older sata drives.
