Wont work.
Nothing before the GeForce 2MX was designed with Mac compatibility in mind.
Even then, there are only a few rare PC MX cards that will work in a Mac, even after flashing. Usually, PC cards can't be flashed because the Mac firmware is too big to fit on the EPROM chips on the PC version of the card.
You'd be better off finding a used Mac-compatible card on eBay or something like that than trying to flash a PC card.