If the command doesn't exist, type

locate knoppix-installer

and it'll find it, then type the whole path to the command. If locate doesn't find anything, then you can try

find / -iname knoppix-installer

but that will probably take a half hour to finish. But it will find it if it exists. Did you do this AS root? The root user usually has a different $PATH than a normal user, so different commands will work as root. (To oversimplify a bit.)

So far as dependency problems and whatnot, that's what Gentoo is for. What programs are you looking for? If you tell me, I can see if they exist in Gentoo.