Just extract the original bios you download from HP, inside the extracted folder you will find "flash.exe" run it after you replace the .rom file with the modified one.
The last time i did that (5.23) my pc just froze and i had to shut it off. But the bios update worked randomly...
Also it is not possible to update the bios from dos, because AWARD flash utility complains that it is not award bios file. So please 911medic can you check your mod again, this board is orginally is ASUS board manufactured for HP. As i know this method of moding "pkey/marker" is working fine with ASUS boards????
I tryed to flash from DOS, But AWARD flash utility giving error message that this is not AWARD bios file.