I’m writing this mainly for my own reference. I note that a lot of people want to install Ubuntu on a laptop but choose to put it on an external USB hard drive. The result is usually that GRUB breaks when the external drive is not connected since it cannot locate the files needed to boot which are on the external drive.
Once I get the kinks worked out I’ll post this to a wiki page. Feedback/testers welcome. I am going to test this with the 64 bit version of Kubuntu on a Dell D620 laptop. The process should be similar with any version of Ubuntu and any laptop that supports booting from a USB device.