Yes this does work,
just use iprep to format and make the thumb drive bootable.
Add dosflash and the hacked firmware.
I tried to boot into dos but it froze at the bios because even the unpowered connected xbox will cause this.
So I disconnected the sata and booted into dos.
Ran dosflash to see my ports but it only shows ide ports.
So this time I left my HD connected and booted into dos and ran dosflash and then it showed my sata ports with my HD connected.
Without powering down the pc, I removed the sata cable and plugged into the xbox and powered it up.
Ran dosflash and it did not freeze and it showed sata ports with a device hooked to one of them.
Ran dosflash and it erased and wrote to the drive.
Done and Done