yes, it can be installed (sort of) i would NOT recommend it though.
Knoppix is not intended to be installed, it was jus a neat "trick" added to a much earlier version hat somehow has kept hanging on.
as Knoppix is more or less a tweaked Debian install, it is tweaked to allow it to run from CD/DVD and few other things, this makes it break things when installed, i would recommend a pure Debian, possibly ubuntu or xubuntu, this as these ARE intended to run from hdd and tend to work great.