You can do it this way too, but I think that one of this two things will happen:

a/ when you burn it and boot from the new master, it will either overwrite or ignore the /etc/X11/XF86Config-4 that you've left on the CD, or

b/ it won't start X if the computer does not have a nvidia card

Judging by your last post, maybe option b/ is OK for you. However, I like to keep my Knoppix as "portable" as I can. You never know...

PS: I'm not going to try it, so if you go ahead tell me if I'm wrong.