Hi Evan,
Jianwei is right.
I'd recommend rebuilding the model as a low polygon version in SketchUp ... you'll have to break up that model into a large amount of pieces and then you might also have issues with normals and degenerate faces.
In other words ... there is no shortcut. But I'm sure you could create a reasonable copy of that model in a few dedicated hours in SketchUp. If you didn't make the model above make sure you reference the other persons work ...
Cheers