TOSHIBA QOSMIO G50 Need help modding bios for (old) new cpu

Hello,

i would like to upgrade my CPU on TOSHIBA QOSMIO G50 and bought 2 but there are not fully supported (multiplier is not OK).
Original CPU is P8400 (2.26GHz)
P9500 works but multiplier is not OK : 1600MHz instead of 2533MHz (i tried to disabled auto adjust throttle in bios but 1600MHz stay the max).
P8700 : same as P9500, multiplier is not OK

I would like to install only 25W TDP CPU, so no T9600 / T9400 (35W TDP)

Extract of service manual :
Microprocessor
The QOSMIO G50 computer is equipped with an Intel® CoreTM 2 Duo Processor.
These processors incorporate a math co-processor, a 3MB or 6MB L2 cache memory.
The PC comes in with one of the following speeds:
Intel® CoreTM 2 Duo Processor (Penryn)
T9600 (2.80GHz) /T9400 (2.53GHz) / P9500 (2.53GHz)
In the case of Processor which built in 6MB L2 cache memory
P8600 (2.40GHz)/ P8400 (2.26GHz)
In the case of Processor which built in 3MB L2 cache memory
These processors operate at 1066MHz bus clock (FSB).

Wich tools can i used to try to mod the 2.30 (last) BIOS ?
It's a PM45 + ICH9M but i dont know the maker of the BIOS (nothing written on it).
Of course, my work (new bios) with your help will be shared. It's just a shame that TOSHIBA dont support more CPUs as it must be simple (same series, just frequency is different).
Thank you,

Edit : forgot to say i ever tried Flash Programming Tool, AFUDOS/AFUWIN, v4 in DOS without success.
CPU-Z extract a BIOS file in .TXT but dont specify more informations.

[attachment=23791]

  TOSHIBA Qosmio G50 v230.txt (Size: 288.2 KB / Downloads: 1)

Sebastien