Flashed my Benq yesterday (my first flash ever), seems to be pretty easy.
I had some problems on my own motherboard (Nforce4), couldn't get the dosflash tool to read the original firmware. So I went to a friend of mine (who has a VIA chipset --> We did need to set his SATA to disable BOOTROM in BIOS).
Was pretty easy, just boot with bootdisk, run dosflash.exe with the appropriate arguments and it worked like a charm.
The things I did.
1. Create bootdisk and put dosflash v1.3 on it.
2. Booted PC and Booted XBOX360 (XBOX360 with his own psu)
3. Then I started dosflash.exe
4. Pressed 'Yes'
4. I had to turn of my XBOX360 for about 2 seconds and put it back on.
5. Dosflash started to read my firmware (took about 2 minutes I guess)
6. Rebooted to Windows
7. Made 4 backups of my original firmware :-P
8. Then I copied my firmware in the Xtreme package which just came out. (named orig.bin, need for batchfiles)
9. I ran the .bat script in the package.
10. Copied the benq-ix.bin from the same directory to my floppy.
11. I rebooted my computer and the XBOX360 again.
12. Ran dosflash.exe with the ERASE!! option
13. Ran dosflash.exe with the WRITE optoin
14. Pressed 'Yes'
15. I had to turn of my XBOX360 for about 2 seconds and put it back on.
16. Dosflash.exe started to write on 4 banks.
The reason I say that you FIRST need to erase it, is because you will probably get an error if you try to overwrite it (that's what happened to me).
After you erased the current firmware and after that write the iXtreme firmware you should be fine.
Took about an hour for me to open/flash/close the XBOX360.
Commands used.
CODE
dosflash.exe r b400 1 a0 1 4 a:\orig.bin
dosflash.exe e b400 1 a0 1 4 D8
dosflash.exe w b400 1 a0 1 4 a:\benq-ix.bin
c000 was primary SATA
b400 was secondary SATA
Hope this helps for some of you...
Cheers,
-pikah
EDIT: Afaik you can only play stealthed backups.