I'm working on a version of Knoppix for AMD64, and also publishing how its done in the hopes that a 64bit version will be released as often as the 32bit version.

I will try what you mentioned. I am posting my efforts here http://www.knoppix.net/wiki/Debootst..._x86-64_LiveCD
I don't have a working version yet, I can't wait though.

Thanks,
Richard Jenniss.