It's not really that. It's that the kernel has certain limitations when you're booting from CD, and it needs the i2c support. I don;t know how to go about installing i2c in the kernel without fubarring its ability to be booted from the CD.

I'd have to make a script that saved your lm-sensors configuration while running off the CD- they are kept in /etc not in /home/knopppix, so persistent home won't work.

But following this procedure after a hdd-install should work just fine.