By what mechanism could the Bible be inerrant?

For those who believe in the inerrancy of the Bible (or those who understand the positions of those who do), how can the Bible have this status given all the opportunities for any message delivered by God to be corrupted by human failings? In particular, humans have free will and thus fell; but a being with free will may choose to convey a different message than one they have been given, and even without such will, imperfect beings make mistakes. Did God suspend the exercise of free will and ability to err (at least without catching it later) of those who wrote the Bible and those who transcribed it?