In the Poser 6 Libraries window, the highest level folders are, by default, "Poser 6" and "Downloads".   You can create a new one to contain the "Miki1020" folder.   Click the little black arrow at the top right of the Libraries window and select "Add New Runtime".   It will prompt you for the "Miki1020" folder.   The alternative is to drop the conyents of Miki1020 in the corresponding libraries in the Runtime folder.   That way ends up with a much more complicated runtime, though, so semidieu's solution is better.