Installing themes?

Maybe I'm an idiot, but this is so simple and basic that I don't think so?

I downloaded some theses and spash screens from kde-look.org and I want to install them. So I extract the folders in the tar balls and try to add them using the Control Panel -> Appearance > Spash Screen/Theme Manager windows. But the theme files are filtered out even though the file names are plainly index.theme or Theme.rc.

I'm pretty sure I've added themes before in KDE with actual hard drive installations - is there something about Knoppix that prevents this?

Thanks.