Remastering a Custom Knoppix Distribution, Part 1 has a detailed article focused on remastering Knoppix 3.8.

There are many reasons to want to build your own distribution of Knoppix. By doing so, you could have privately-written software distributed in a complete environment, create a reduced toolset for your specific needs (saving valuable space), or explore and release a particular focus (adding to the growing list of pre-fabricated specialized options).