I think it's already been said in this thread a number of times, but just to spell things out clearly for the OP:
Getting Xell into the nand flash can be achieved a number of ways - in-place using the LPT or USB programmer, or by removing the nand chip itself and using a stand-alone programmer.
How you get Xell into the flash is completely unrelated to the 3 JTAG wires - No matter how you get Xell flashed into the Nand, the 3 JTAG wires (including diodes) are required to actually make Xell boot - the Xell software itself uses the 3 wires to function. Without the 3 Jtag wires, it will not work. Period.
As for the CPU key, that is stored inside the CPU, not inside the Nand, so you can dump your nand however you want and will still not get your CPU key from that alone. The only way to extract it is to successfully flash Xell into the Nand, apply the 3-wire Jtag hack, and then boot Xell.
That is pretty much that.
ok HB i ll try your advice. You say "i need jtag wiring in anyway to hack". You are the only one who understand me. I thought jtag wiring meant for only flashing nand which means i am wrong

it is meant to boot xell
Thanks for your comment
So, a professional does not know how to read... and does not know what a jtag port is?

?
You are brilliant!
wire the diodes and jumper wire, resolder that nand, and read like a lot more.
Also, you should improve your English.