Well, so here is the PSD file with the book. I made some tweaks and tests and It looks quite good even ingame converted to HeXen palette.

So if you want to make some experiments, here you go:
https://www.mediafire.com/?g82ta4iyd5ey14zFirst you need photoshop - sorry no free software variant.
It have animation defined, so to properly use the file, enable the animation window in your Photoshop. You can then view all the frames.
To switch different versions you enable/disable the corresponding groups in first frame - it will propagate to all others automatically. Changing it while any other frame is selected it will change only that one frame.
To change the inscriptions on the pages/cover you have to edit the smart layers called left, right and desks. It will automatically update on all the pages. I have there original HeXen II pages from Necromancers book and some of my own designs.
To make the correct usable animation you will probably have to play with it a little more than I originally wanted but its not that hard. You just have to copy and merge some layers.
I will probably later add some new features. Probably including hands and Tome of power skin.
For now good luck.