I dont know if that is right. If you're computer dosent POST, you have no way of accessing the floppy drive, in turn granting you no access to flashing your bios. POST stands for Power On Self Test, it is the very first thign your computer does when you turn it on. When your computer dosent post, you have major problems.
Unless you have to start it with a cpu that dosent need the update, flash it, turn it off, change the cpu, and then turn it back on. But that hardly seems practical.