Actually, I was thinking of Psalm 22, which was most likely written quite some time (centuries?) before crucifixion as a method of punishment was widely in use.
There is really no evidence that crucifixion was not in use. As I said, Deuteronomy (or Leviticus) make mention, and it is certainly known to have happened in Egypt, out of which the Israelites came (prior to the Davidic Kingdom and therefore the Psalms).
Crucifixion, impalement, branding, all manner of tortures have been around since the very beginnings. There is nothing new on this earth. What is missing is the evidence thereof. We don't have the writings of the earlier peoples in abundance like we do the Egyptians and Assyrians forward.
While I am against your position generally, it is the historicity of this remark that I challenge. If you would care to offer up another example, that would be fine - But crucifixion, as a general means, does not fit the bill. The nails, perhaps, but not the crucifixion itself.