I got almost the same error (without that part of a missing cloop module) when trying the following:

I created a cloop image based on the Knoppix 3.3 from November, then i copied the kernel and isolinux stuff from c't edition to the master directory and exectuted a mkisofs command as stated in the isolinux documentation. Any ideas why it states it can't find the knoppix filesystem. It is there, on the usual location ...

thx,

daja