Works a treat
just what i did.. if anyone cares..

a) create a boot floppy (or usb etc) and just copy dosflash16 over and the benq1.1 directory

get the correct drive number, from msinfo, or use iprep to get the number, mine was d480. Its quite obvious when it pops up in iprep. You do not need iprep any more.
c)unplug sata drive, reboot go into BIOS (mobo) and change it to boot from USB/floppy etc as needed (i actually used a Mini SD card !!)
d) turn off machine, plug in xbox and connect drive to the first sata port, do NO switch on xbox
e) boot to floppy.
f) from the dos prompt A:\> i typed in:
dosflash r d480 1 a0 1 4 a:\orig.bin 0(replace d480 if needed)
i) a prompt comes up.. hit yes
ii) turn on drive, wait 2 secs some hex codes will start changing
iii) turn off and wait 2/3 secs. hex code will now stay static
iv) turn on.. the drive will dump.
v) I did this two times to take two back ups.
g) create the ibenq fw, I just ran (from the fast directory):
firmwaretool a:\org.bin a:\benq\fast\benq-iax.binYou will see the drive key etc come out, i guess you redirect if need to a file, or use another tool to read the key out (toolbox). I Now have the hacked FW in the fast directory.
h) reboot.. and run:
dosflash w d480 1 a0 1 4 a:\benq\fast\benq-iax.binGo thru the same on/off routine as f), then this will flash the drive...
However, mine flashed but came up with errors. I wanted a clean flash, so i:
i) (without rebooting etc) just typed:
DosFlash e d4801 a0 1 4 D8 0
ii) then reflashed:
dosflash w d480 1 a0 1 4 a:\benq\fast\benq-iax.bin
This worked.
Now just turn off the xbox unplug and good to go. (takes about 5 mins)