Hi AlejandroPadrino,
I'm not sure what you do mean with "default modules". Kernel modules? Extensions?
You want to modify an ISO image without to do a remastering, right?
May be, there is a way, but I don't know, how to do it. You want to put default .tcz files into the image, right? But why? They are already there!
After booting the system (no matter if installed or as life system) you than can install/load whichever extension you find in the repository, at least in cloud/internet mode if you haven't persistence yet. Where is the problem now?
You mention the /cde directory. You can't edit files there, because it's a read-only directory. It for that seems to me you didn't yet do an installation and are running the system as a life system, right?
Now make an installation and enjoy TC!
Very good installation instructions you find in the Corebook page 11 through 21.
Volker