Sean: The blurb in the book stated that she uses no digital manipulation other than taking scans of the prints, but I agree with you about not knowing exactly how she ends up with that look. I spent a long time thinking it through and am still not sure how she does it. For a while I thought she might have been scanning an inverting the goop side because that gives you those yellows and some of the artefacts/tears/scratches could be explained that way, but you can clearly see paper tears too on the same shots, so that would suggest they're proper prints and not goop scans. 
Some of her more recent shots are very blue, though, so maybe the ones in the book I saw were shot a few years ago? Either way, that book is worth hunting down because it's huge and there are a LOT of photos in it.