JTAG Tutorial for the USB NAND Flashers
Here you can find all you need for it.
Schematics etc if you need help or got any questions come on the chat there usually is always somebody around:
Chat -> http://chat.xbox-experts.com
Tutorial/Wiring etc -> http://jtag.xbox-experts.com
Notice: The Tutorials have been done many times and were often successfull, however we cannot guarantee the success and so dont take any responsibility for any damages that might be caused by it, you do it on your own risk!!!