Can't you simply flash it with the mac bios on a pc in dos? It will not work in the pc after flashing (and a restart I guess) but it will have the right bios for a mac at that point, right?
I would try that..
And if you have the one with the socketed bios I would simply order a new bios chip and flash that with a programmer, and keep the original in case something doesn't work right.
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