If you want to know how to edit the textures (thats the xbm files) read here
Ok ;) Firstly, this is not "my invention" i just think that this needs to be spelled out properly for more mods to come faster.
So here it goes.
All credits go to the guys in this topic http://forum.xentax.com/viewtopic.php?f=10&t=6634&start=15 - they made the scripts to unpack it.
Download QuickBMS here - http://aluigi.altervista.org/papers.htm#quickbms
Second, Download this txt file - http://filesmelt.com/dl/scriptw2.txt
(which is what chrrox posted in the 3rd post on page 2 of that topic, just in textfile form to make it easier)
Third, unpack quickbms, put the text file in the same directory.
Now start quickbms64_test.exe point it to the scriptw2.txt then point it to the pack0.dzip in The Witcher 2\CookedPC
Extract it to a location of your choice (not in The Witcher 2\CookedPC though!) it takes a while
Again, all credits go to the guys on xerrox and particularly chrrox. I did not write anything in this script myself, i am just putting it together so everyone can get to the files and try their hand modding. The contents of scriptw2.txt are identical to chrrox's post i linked to, so you can just copy that code segment into your own text file and get the same file that i uploaded on filesmelt.
Info: I claim no ownership nor rights to any part of anything i linked to.