How to create a bootable USB stick for NetBSD 5.0

[piminx%comcast.net@localhost]

I'm running on an i386 w/NetBSD 5.0:
 
# uname -a
  NetBSD bigbox 5.0 NetBSD 5.0 (BIGBOX-$Revision: 1.915.2.3 $) #20: Mon Aug 17 
16:56:52 PDT 2009  
root@bigbox:/home/spamd/NetBSD/usr/obj/sys/arch/i386/compile/BIGBOX i386
 
I've been trying to install NetBSD-501-PATCH on an HP/Compaq Desktop D530 
Ultra-Slim (i386).  I installed XP (BOOooo), it seemed the easist way to 
install all the latest firmware gunk for the box.
 
I'm having trouble creating (and, later, perhaps installing from???) a USB DVD 
writer/reader.  

  umass0 at uhub4 port 5 configuration 1 interface 0
  umass0: Memorex USB 2.0 Drive, rev 2.00/1.19, addr 2
  umass0: using SCSI over Bulk-Only
  scsibus0 at umass0: 2 targets, 1 lun per target
  cd1 at scsibus0 target 0 lun 0: <Memorex, DVD+-RAM 525G v1, G.01> cdrom 
removable
  cd1(umass0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
    SENSE KEY:  Not Ready
     ASC/ASCQ:  Medium Not Present

Many thanks to Matthias Scheler for getting my head a little straighter on 
iso-image, mkisofs, cdrecord and growisofs.  

The HP box says it can boot from a USB device (USB 2.0 on board).  NetBSD says 
it can deal with a KINGSTON DataTraveler 2.0 (oh gee I have one - 16GB and 1GB) 
so it occurs to me that this might be a better option to try for a while.

  umass0 at uhub4 port 6 configuration 1 interface 0
  umass0: Kingston DataTraveler 2.0, rev 2.00/2.00, addr 2
  umass0: using SCSI over Bulk-Only
  scsibus0 at umass0: 2 targets, 1 lun per target
  sd0 at scsibus0 target 0 lun 0: <Kingston, DataTraveler 2.0, 1.00> disk 
removable
  sd0: fabricating a geometry
  sd0: 953 MB, 953 cyl, 64 head, 32 sec, 512 bytes/sect x 1952768 sectors

The NetBSD box can mount the USB stick from /dev/rsd0e.  I have set partition 0 
to be bootable (I think) installing /usr/mdec/mbr.  

  # fdisk /dev/rsd0d
  Disk: /dev/rsd0d
  NetBSD disklabel disk geometry:
  cylinders: 953, heads: 64, sectors/track: 32 (2048 sectors/cylinder)
  total sectors: 1952768

  BIOS disk geometry:
  cylinders: 969, heads: 32, sectors/track: 63 (2016 sectors/cylinder)
  total sectors: 1952768

  Partition table:
  0: Primary 'big' DOS, 16-bit FAT (> 32MB) (sysid 6)
    start 128, size 1952640 (953 MB, Cyls 0/2/3-968/20/20), Active
  1: <UNUSED>
  2: <UNUSED>
  3: <UNUSED>
  Bootselector disabled.
  First active partition: 0
  Drive serial number: 67305985 (0x04030201)

I'm unclear if I'm doing this correctly.  The current fs on the USB stick is 
FAT16.  
Should I newfs the USB stick?  If so to what? (A unix fs seems more sensible)  

Is /usr/mdec/mbr the right boot record to have on the USB stick?

Should I copy boot-big.fs or something else and will cp do what is needed or do 
I need some other program/script to get the install image correctly on the USB 
memory dongle?

TIA,
Paul