The 3.5cm f/1.8 W-Nikkor is easy as it has its own focusing helicoid, plus external mount. The situation is different for the 5m f/1.1 Nikkor-N if you have the version with internal mout. In the latter case you definitively need some kind of helicoid adapter in order to focus the lens -- at all. Thus, unless you have such adapter, I would forego the internal mount lenses, also included the much cheaper 5cm f/1.4 or f/2 models, and aim for the 5cm f/1.1 with external mount. Or search for any of these 5cm lenses with a Leica 39mm thread natively.
You can also hobble together your own focusing adapter if you have the S-mount bayonet (internal). Cheap Russian Contax-copies would be a source for that item.
