I'm not sure that I understand your challenge completely or your motivations for it (or your posting it in this forum, for that matter).  I myself do not believe that the Bible is the literal "Word of God" anyway, so I'm just arguing for the sake of argument here.

I've always found the "Word of God" argument to be tenuous myself.  Most (if not all) Christians and Jews will agree that the Bible was written down by men, and lots of different men at that.  Of course, they may argue that god inspired such men, but then they have to also argue that god inspired the men who passed it down, the men who translated it, the men who compiled it, and perhaps even the modern publisher who prints it.  I could also point out the fact that the Eastern Orthodox Bible has more books in it than the Roman Catholic Bible, which itself has more books in it than the average Protestant's Bible, which is itself demonstrative that the idea of what is "divinely inspired" can be changed over time or within a single church community.  Do Protestants think that Eastern Orthodox Christians (who are, we should note, the oldest living Christian tradition) are wrong about their Bible?  Did god inspire the Orthodox Church to keep some books and the other churches not to?  That seems pretty unusual, don't you think?

Also, if the book is inspired, then god is a strange fellow.  He contradicts himself often, doesn't he?  And in the Old Testament he seems like nothing more than a pagan patriarchal figure, not much different in his sense of humanity than figures like Odin, Zeus, or any other such father god, quick to anger and slow to mercy.  Suddenly in the New Testament he is an enlightened godhead offering his infinite mercy to those who would accept his sacrifice.  What an odd fellow indeed!  

I'm more inclined to believe that the book isn't inspired by god at all.  Otherwise, we have to imagine that god is something of a fool, contradicting himself and proposing all sorts of nonsense.  And yet another problem we run into is the lack of timelessness of the Bibles edicts.  Should I really sell my daughter to her rapist for 15 shekels in order to prevent a scandal?  If that's the case then Elizabeth Smart's captor shouldn't be jailed, we should just be marrying her off to him.  (That was meant to be absurd people, don't be offended.)  If this is the timeless word of god, then god sure is stuck in the Dark Ages, isn't he?

What I never understood is why the Bible has to be the "Word of God" anyway.  It's a book of myths and legends and pseudo-history like anything else.  It's comparable to the Odyssey, the Norse Sagas and Eddas, the Mabinogion, and other legendary compilations of stories involving deities, heroes, and pseudo-historical figures.  Why can't they just be treated like stories instead of absolute timeless facts passed on by god himself?  Would your faith in god really waiver if you just said that the Bible was written by man about the issue of god, and not inspired directly by god himself?  It's not like it would invalidate the Bible as a holy text, and the advantage to that approach is that you leave room for more literature.  If this religion is so timeless why hasn't anyone been "inspired" by god recently to throw in a few books, because god knows we surely need some literature that speaks in terms of our modern society.

Again, I'm not sure about your motivation for this argument, but I'm in agreement that it's a little silly to call the Bible the Word of God.  I understand why it is done: to validate the Bible entirely.  However, stories don't need to be validated by divinity in order to spread their messages to people.