I installed the miniroot on my DS2100 using my i386 box to run disklabel.

Copy disklabel.h and machine/disklabel.h (rename it :-) into a directory with
the plain old NetBSD disklabel sources, change the inclusions in the source
files so they get your local copies (you'll need to change the inclusion of
machine/disklabel.h in disklabel.h as well), and change the Makefile to compile
with -Ui386.

It Just Works.  And it'll install the disklabel in-core on the running system
on your i386 so you can do stuff to the disk until you reboot, even though
the i386 kernel won't look in the right place at boot time.

Thor