Nothing says it can't be done. Rest assured, it can. It's a question of difficulty and expertise.

If you install to a hard drive, even if you want something Knoppix doesn't already have, apt-get or dpkg-X can get it.. From your post, I assume you don't know what you need to make what you want. That's why I recommended the Bible book... it offers a lot of hand-holding on Linux: ip-chains, etc.

If you want it completely on the CD, you *MAY* have to remaster the packages/settings. Remastering is not for the feint of heart.

There is some room on the CD, especially if you Hack some of the PDF files. If you don't want to do much, you can probably set up a login script in the KNOPPIX folder that takes care of it all... but, it assumes you have a background in Linux.

As for PR: with kick-butt $40, 5"x5"x2" routers out there, anything that takes the above kind of expertise just isn't impressive... except as a learning experience.