Gutsy on one partion/Hardy on another

[NoOp]

What is the easiest way to install Hardy on a separate partion?

Here is the situation:

A friend has Gutsy installed on sdb1 (swap on sdb5), so he'd created a
second partition (sdb3, swap on sdb6) and installed Hardy Alpha 6 into
sdb3. Unfortunately he ended up with a Busybox intramfs on boot. So
after a couple of days of emails I finally got his grub & fstab back to
normal (it was pointing to sdb3) by putting grub on sda1 (his Windows
drive) and pointing root back to his gutsy sdb1:

sudo grub
grub> root (hd1,0)
grub> setup (hd0)
grub> quit
Reboot (to hard drive).

All is well again with Gutsy, but now he'd like to try again; this time
with Hardy Beta on sdb3. I'm reluctant to have him just go ahead and try
the install (alternate CD) again without some guidance from the list.
So, any advise on how to go about this without having to redo grub &
fstab edits again in case of failure/Busybox?