Hi there,
just came back after ~one year since i discovered there is a forum about DCOTE.
I do not know if it is of some interest, but back then i wrote a little tool, that allows to extract nearly all of the textures of the game and in turn inject them (altered/exchanged) back in the game. Nearly all means lots of textures of the environment and so on but at least i never found eg a weapon texture(?) being extracted. The tool itself is coded in Java and as it is more proof of concept so the usage is in no way foolproof but if you carry out the instructions it should work straightforward. The textures are exported as single *.dds files.
I did not do much testing, but exchanged a wood and a carpet texture and found it worked in game. Unfortunately i do not remember things about size limitation. Maybe one could only inject textures of the same size back into the game. As far as i remember i took a very high quality wood texture and downsized it to be exchangeable. It looked quite well in the game being much sharper than the original texture.
On top of that i fear it could be kind of illegal to alter the game without permission. (If so and the moderators or anyeone else do/es know, i apologize...just let me know)
Maybe someone is still interested or could help out with the legal issue?
On the other hand someone mentioned tools that may have been already published and do the same? So in that case it would nevertheless be nice if anyone could point that out more in detail.
Though i planned to do my first HiRes Texture Pack, i found myself totally overwhelmed by the huge amount of textures in the game. I am more a coder than an artist so i stopped working on that, as i realized there is no simple photoshop batch processing to get high resolution textures...

cya
Korgull
edit: ok, i found svckleads extractor mentioned somewhere here, so maybe my post/my prog is obsolete.