You need three files msdos.sys command.com and io.sys to boot into a dos environment.
To Format the USB Stick , I used to the HP Utility called HP USB Disk Storage Format Tool . Run the HP utility with the location of these 3 files and you are done.
Once the formatting is done copy the utility to flash your rom and the image to flash it with on to the USB stick.
On LV678 the BIOS saw USB stick as a hard drive and I raised its priority ahead of the SATA disk and the machine booted into the DOS environment.