I think you might be able to right-click on a file in Windows and Open With MC? If your file assocations are set so that MC is the default program then double-clicking on a file will also work.
There might be a "file/folder" view within MC that will allow you to view the contents of your disk without importing them, but not sure - have a look around!
However, if you want to be able to sort and categorise your files in some way other than your physical directory structure then you will have to import them into the program, tag them properly, and set up your custom views.