When you go to extract the sets do you get to point where it asks what type
of filesystem you want to use?  What are you trying to extract the sets from
(cd, harddrive, tape)?  The script I agree leave a little to be desired and
I had a problem when I recently installed 1.3.2 myself.  However I kept at
it and was successful.  There should be nothing in the script to crash
NetBSD though or at least I never had that problem.  Make sure you print out
the install script that is with the archive and then when you get to the
point that you have a problem let us know what step you are on.  There is a
good set of articles on how to install NetBSD running in "Amazing Amiga"  I
have clipped all of the articles out and made my own NetBSD binder out of
them along with the install scripts and stuff.  In the Install text there a
couple of times that you have finish one section of the install ant then
halt and reboot with a different loadbsd option.  Anyway I am rambling on.
Let us know the answers to the question I have asked and we will try to
help.