Does it need to be a CD? If not then have you tried the Knoppix DVD version.
I don't have it to hand so I can't check if it includes the C-shell at the moment, but it does contain a lot more software than the CD version, so it may include the C-shell.
Another alternative - if you are feeling adventurous - is to create your own Live CD. Instructions are provided at:
http://www.knoppix.net/wiki/Customizing_FAQ.
It sounds as though it's fairly easy to do, as long as you are just wanting to add/remove a couple of applications. It will while away some time to do though.
Alternatively you could try some of these less well known Live CDs. I believe these all include tcsh, but I haven't tried any of them.