I just created one using this how-to (the main site is down, but here's a mirror):
http://hints.us.linuxfromscratch.org...ot-cd_easy.txt
and there's a couple of other methods here:
http://hints.us.linuxfromscratch.org/
I'm sure you will be able to apply the technique to redhat... you WILL need another system to do this though.
The thing is... It will be extremely hard to get something working as well as knoppix. You have to write code in the startup scripts that searches for certain hardware and loads those modules. There might be an easy way around it... but I can't think of one (please let me know if you do).
The cd I created works great, It is just like a bootup cd, only I have all the tools of a complete system! (I am actually using it to make an install cd of lfs, so you don't need a base system) however, I didn't even try to incorperate X or network stuff.... that's the hard part I was talking about. (If you know the systems you will be booting, I guess you could make it work o.k.).
well, have fun
-Adam