Same here and I am using KDE 3.4.
The themes I downloaded have a <theme name>.themerc...which is also not visible in the themes list.
From what I can see, when you create a new theme from your current desktop, a <theme>.kth and .xml are created. No place to import from a themerc file.
I really wish that theme makers would start including *ALL* the required files needed to install themes or at least the developers should include some way to import other file types.