The chihiro mobo uses the MCPXII southbridge chip. It's the same used on debug xbox motherboards. A retail motherboard uses the MCPXIII. That one has 512 bytes rom onboard that are the code the system initially runs at startup. On the MCPXII, that code comes from the tsop flash chip.
Next, there is the challenge protocol with the smc chip that only is present on retail motherboards. It's purpose is to prevent single stepping trough the bios. After a reset, the smc chip provides 4 bytes and expect you to do a calculation with them. It finally needs 2 bytes in return. If this challenge protocol isn't furfilled within a fraction of a second, the smc chip will reset the x86 architecture so it can try again. If things go wrong for 2 or 3 times, it initially gives up and keeps the system in a reset state. At that moment it flashes the 2 status led's alternating red and green which is described as a frag (flashing red and green)
So, desoldering the flash chip and reprogramming it is a bit short trough the corner. If you would replace the smc chip and mcpx chip at the same time, it would probably work, but I doubt you will find MCPXII chips from a trusted distributor. It's a nice bga package. Not impossible to replace, but not for the average joe.
In case you still might consider it, also bear in mind that there are 4 different motherboard revisions. 1.0 and 1.1 motherboards used a connexant video controller. The 1.0 MCPXIII chip is different from the 1.1 MCPXIII boards. 1.4 revision motherboards used a different focus video controller. 1.6 revision motherboards don't have the solderpads to increase the ram memory. So, besides the fact they use an xcalibur video encoder with buildin maskrom, they are not interesting for this purpose.
Basically, there a 7 different revisions 1.0 1.1 1.2 1.3 1.4 1.5 1.6 and 1.6b.
1.5 is so seldom seen that people often think it was just a bad production batch.
1.6 and 1.6B differ in memory chips. 1.6b used hynix chips that are slightly slower. (others use samsung)
1.2 and 1.3 boards had a smaller tsop flash chip installed. 256KB instead of 1MB on previous models.
Some models have signals removed from the LPC pin header (like the lframe)