I've considered this subject myself. I think that before LDW would answer that, they would want to see a draft copy of the book. After all, it's more than just the copyright on the name to consider.

My guess is that the book would have to meet the same guidelines as fan fiction. I.e. it would have to be suitable for audiences of all ages; would have to be true to the story line in the games; and could contain no violence; mature themes; or cursing.

You also would have to consider whether or not you were willing to share your royalties with them? I don't know that they would insist on it, and I doubt it would make a big difference in their decision, but it is something you would have to consider.