For the record, let me say that I do not claim that God is timeless. I claim that it is logically possible for God to be timeless and such a state of affairs is consistent with free will...
Fair enough. Do you believe that the "timeless" position negates the argument in the OP? I don't see how it does, but I'm open to explanations.
The open theism position is another possibility with its own set of assumptions about the nature of God and time...
True, but it is immune to the argument in the OP, and Open Theism seems partially motivated by a desire to circumvent such arguments.
I took a look at the Wikipedia entry. Looks like Lakoff and Nunez have their share of critics -- whether the criticisms impact the particular point you cite for them here, I cannot say at this point.
Quite so, but even God has his critics, doesn't he?

Lakoff and Nunez are open to challenge on a number of issues, but I think that their general approach to cognition--that all human knowledge is ultimately grounded in bodily experiences--is a reasonable assumption. Lakoff has promoted this idea since the 1980s with lots of data on the use of metaphor and analogy in language. It's quite an impressive body of work.
...The basic equation speed = distance / time does not suggest that a car can travel at a particular speed either. But if a car travels at a certain speed then it will cover a certain distance in a certain amount of time. Likewise, the limit equation does not address whether a being can travel at an infinite speed, BUT if a being CAN travel at an infinite speed, then the equation suggests such travel will take no time at all.
And your point is what? If you are permitted to do division by zero, God exists? I will concede that God is as mathematically justified as Santa Claus.
3. Infinity can only be understood by analogy.
You mean by humans. That does not mean an infinite something-or-other cannot actually exist. It certainly seems logically possible for there to be an infinite amount of space or an infinite amount of time. Why not a being that "moves" at an infinite speed?
You are missing the point. I'm not arguing that reality can be ultimately be made fully sensible in terms of human experiences. I am pointing out that statements such as "God exists" can only be asserted if they make sense to human beings. If the Christian God ultimately fails the comprehensibility test, then nothing that humans say about him can be taken seriously, including the properties that they attribute to God, e.g. that the God is somehow "supreme", "omnipotent", "omniscient", "good", or any other quality that can only be understood in terms of human sensibilities. The minute one retreats into the ineffability defense, all statements concerning God become inherently meaningless. There is no point in worshiping incomprehensibility, and, indeed, no one really does. Ineffability only comes in handy as a defensive shield against reasonable discourse. Christians, hypocritically, drop the ineffability defense at the first opportunity. They show up in church, worship their god, thank him for imagined favors, and pray for more favorable consideration in the future. The minute someone asks to make sense of such behavior, it is back to arguing division by zero.
For a timeless God, "will" would be a state.
Well, that is problematical, because "will" is a verb, and verbs cannot be used to denote states. Adjectives can. You can talk about a "God that is willful", but not "a God that is will". The concept of "will" is inherently bound to causation, as is God, the "First Cause". Semantically speaking, causation always describes a temporal relationship between two events. In the case of agents, "will" only makes sense as a factor in the antecedent event of a causal relation. I understand your statement here in a procrustean sense--that you must declare "will" a state, because that is the only way to make it fit your preconception.
On the open theism front:
God's omniscience can be reconciled with Him not knowing the future if the future is something intrinsically unknowable. Under that view of time, it would be impossible to use a time-machine to travel to the future -- there being no future to travel to. God could make good guesses about the future, just as humans do (probably far better than humans) and He could of course decide in advance that certain things will happen and so know the future to that degree. God is still omniscient under this view because He knows everything there is to know.
I like the argument in that it does circumvent the argument in the OP. I suppose that the problem is in getting most Christians to buy into it, because the traditional view is that omniscience includes knowledge of the future. The whole point of the OP is that knowledge of the future precludes free will. If God cannot know the future, then more than one choice is possible. There may be other good reasons to reject belief in God, but the argument in the OP would not be one of them.