Does it work to simply write an ISO to a slice of a hard disk and
mount it with mount_cd9660?  I don't think I've ever tried this.  I
think I tried it with a USB key once and it didn't, but that was a
long time ago and I'm not even sure I was using NetBSD.  I think I
might've been trying to chainload an ISO image using GRUB, though, so
maybe I just never tried to mount it outright.

--Blair