To mount a floppy disk image:
# vnconfig -v -c svnd0 floppy.fs
# mount /dev/svnd0a /mnt
...
# umount /mnt
# vnconfig -u svnd0
# dd if=floppy.fs of=/dev/fd0c bs=32
To mount a CDROM image:
# vnconfig svnd0 /tmp/ISO.image
# mount -t cd9660 /dev/svnd0c /mnt
...
# umount /mnt
# vnconfig -u svnd0