I had tried your suggestion for disklabel and it still did not work.
However, I had tried the following and it did work:

# disklabel -B -b VS3KBOOT.BIN RZ24
disklabel: warning: boot overlaps partition a, marked as FS_BOOT
disklabel: warning: boot overlaps partition c, marked as FS_BOOT

	I returned to the boot monitor and ran 'b/100 dka0', which is the
first SCSI hard drive. After entering VS3KBOOT.BIN, the boot code ran,
looking for the kernel. I could not copy the kernel onto the hard drive
because it was returning some 'file system full' errors. I have a screen
capture of a session below:

# mount
bootserver:/usr/netboot/netbsd-vax on / type nfs
# mount /dev/sd0a /mnt
ffs: /dev/sd0a on /mnt: Device not configured
# mount /dev/sd0c /mnt
/dev/sd0c: file system not clean; please fsck(8)
 
# fsck /dev/sd0c
fstab: /etc/fstab: No such file or directory
fstab: /etc/fstab: No such file or directory
fsck: cannot open `/dev/sd0c': Device busy
# mount
bootserver:/usr/netboot/netbsd-vax on / type nfs
/dev/sd0c on /mnt type ffs (local)
# umount /mnt
# fsck /dev/sd0c
fstab: /etc/fstab: No such file or directory
fstab: /etc/fstab: No such file or directory
fsck: vfstype `unused' on partition `/dev/sd0c' is not supported

# fsck /dev/w sd0a
fstab: /etc/fstab: Inappropriate file type or format
Can't open /dev/rsd0a: Device not configured
# fsck /dev/sd0
fstab: /etc/fstab: Inappropriate file type or format
fstab: /etc/fstab: Inappropriate file type or format
fsck: cannot open `/dev/sd0': No such file or directory

# set
HOME=/root
PS1=# 
OPTIND=1
PS2=> 
_=cls
BLOCKSIZE=1k
TERM=vt100
PATH=/sbin:/usr/sbin:/bin:/usr/bin
IFS=    

(termcap crap deleted)
 
# cat /etc/fstab
/dev/sd0a / ffs rw 1 1
/dev/sd0b none swap sw 0 0
/dev/sd0e /usr rw 1 2
/kern /kern kernfs rw
# disklabel -B -b VS3KBOOT.BIN S sd0 RZ24
disklabel: warning, boot overlaps partition a, marked as FS_BOOT
disklabel: warning, boot overlaps partition c, marked as FS_BOOT

# mount /dev/sd0e /mnt2
ffs: /dev/sd0e on /mnt2: Device not configured
# ls -l mnt
total 57
-rwxrwxr-x  1 root  wheel  18312 Mar 17 07:10 boot
-rwxrwxr-x  1 root  wheel  19332 Mar 17 07:10 copy
-rwxrwxr-x  1 root  wheel  20372 Mar 17 07:10 edlabel
# cd /mnt
# ls -l
total 57
-rwxrwxr-x  1 root  wheel  18312 Mar 17 07:10 boot
-rwxrwxr-x  1 root  wheel  19332 Mar 17 07:10 copy
-rwxrwxr-x  1 root  wheel  20372 Mar 17 07:10 edlabel

# cp netbsd /mnt
/mnt: write failed, file system is full
Apr 23 18:00:24 myname /netbsd: uid 0 on /mnt: file system full
cp: /mnt/netbsd: No space left on device
Apr 23 18:00:24 myname /netbsd: uid 0 on /mnt: file system full
myname# umount -w  /mnt
myname# mount -w /dev/sd0a /mnt
myname# cp netbsd /mnt
 
/mnt: write failed, file system is full
Apr 23 18:01:13 myname /netbsd: uid 0 on /mnt: file system full
cp: /mnt/netbsd: No space left on device
myname# Apr 23 18:01:13 myname /netbsd: uid 0 on /mnt: file system full
mount
bootserver:/usr/netboot/netbsd-vax on / type nfs
/dev/sd0a on /mnt type ffs (local)
myname# fsck /dev/sd0a
fstab: /etc/fstab: Inappropriate file type or format
** /dev/rsd0a (NO WRITE)
** Last Mounted on /mnt
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
5 files, 315 used, 20 free (4 frags, 2 blocks, 1.2% fragmentation)
#

This may help.

Paul Apprich