The easiest quick-and-dirty way is to convert the existing .cr2 file for the book into a .pz2 MAT pose file. (Note that there are lots of other ways, don't take this as The One True Way, this is just what I'm happiest with.)

• Make a copy of the .cr2 and open it in a text editor.

• Right at the top is a "version" section, and a single bit of data between a pair of curly brackets. Keep this bit, and mark all the text from there down to...

• Move down to the end of the file, where you'll find a bunch of "material" sections, detailing all the material names in the object. Scroll up, going over all the materials, until you reach a "figure" statement, which actually contains all the materials (if you note carefully how all the curly brackets go). Delete from your mark at the top down to just above the "figure" section.

• The first two lines of the statement are "figure" itself and an opening bracket. Delete from here (usually for a poseable figure, a Name statement and a few addChild and weld statements, among others) down to the first material section.

This should leave your file as a tiny "version" section and a "figure" section consisting only of a bunch of material statements. Change all the existing file paths to your new texture files, and save the file with an appropriate name using a .pz2 extension. One advantage of doing it this way is that you get a MAT pose that you can apply to the figure, and also change the MAT of the book as it appears in existing scenes.

Another quick-and-dirty way would be to use the Surfaces tab in DAZ|Studio and manually change every single file reference to your new files. This is do-able in something simple like that book, but for anything really complex with lots of different materials and a dozen or more textures, bump maps, transmaps etc., it gets depressingly easy to miss one or two and end up with something that looks really weird.