you can create a DOS boot drive on a usb drive.
I recommend using the HP tool. http://www.bootdisk.com/pendrive.htm
You will also need a freedos folder to point it towards and use the AFUDOS version supplied by the manufacturer.
After you make the boot drive, paste the bios flashing utility into it.
If its AFUDOS (it probably is) the command will be 'AFUDOS *BIOS ROM file* /p /b /n /c /x'
EDIT: there might be a utility to flash from within windows. NEVER FLASH A BIOS IN WINDOWS!!!! I cannot stress this enough. there will be a high chance that it will kill your BIOS in the process.