Pues eso que desde el día 11 está disponible dicho hack, lo he visto en xbins, en su ftp, cito aquí el readme.txt
Finally the Jasper JTAG Hack is here
This is XELL (Redline99's XeLL) inserted into 6723 Jasper-Kernel.
Don't wonder about the Filesize, its correct like that. It just flashes the beginning of the NAND so your console specific data like MAC adress will stay.
Of course you should have a working backup of your NAND before you proceed.
*** NOTE ***
It's for the Large Block Jaspers, 256MB and 512MB
*** NOTE ***
Just flash with:
LPT
nandpro lpt: -w256/-w512 jasper_6723_hack_for_256mb_512mb.bin 0
USB
nandpro usb: -w256/-w512 jasper_6723_hack_for_256mb_512mb.bin 0
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Bliep
Saludos!!!