Here is a little update how everything is done.
First the models are created in the usual modeling software, in this case by Matt in Sketchup. The models are built according to a mixture of plans, photographic and textual references, and educated guesswork.Then, the models are rendered with rendering software, in this case Indigo Render, in order to get a feel for how they will look in-game, and to make sure they check out. Then, the models are sent to Robin Bock, who converts them, and imports them into Cryengine 3, where he does further tweaking of the materials, animates parts, etc. Once that's done, he may take screenshots of the models in-game to share with the rest of you.
That's usually how it's done.