How to boot a memory stick image of a hard drive?

[jmh6]

Hi All,

  Not sure if this is the right place to ask this question?

  I am using latest GRUB2. I have made an image copy of a Linux system 
running on a hard drive with a reiser filesystem. [ dd if=/dev/sda 
of=/dev/sdc ] sda is a PATA hard drive and sdc is a memory stick.

  I can mount the memory stick on a linux box and all seems OK.

  I try to start that image with grub.

  grub> linux (hd2,msdos2)/boot/vmlinuz

  All seems OK. I can see on the memory stick that Grub reads vmlinuz as 
expected.

  grub> boot starts the image. But the image complains that it cannot find 
its root filesystem.

  I have tried many variations on the root=line to no avail.

  grub> linux (hd2,msdos2)/boot/vmlinuz root=/dev/sda2


  I was expecting grub to do whatever magic was needed to make the usb 
stick available to the kernel as /dev/sda2.

  Is this possible?

  I was hoping to be able to migrate an up and running hard disk system 
with lots of live files to a system running from a memory stick.

  Thanks in advance for your time and help.

  John