No, there aren't any adapters to use N lenses on a Canon EOS camera. The N mount is almost as large as the EOS mount making an adapter all but impossible and retain infinity focus. In addition, the N aperture controls are electronic even though you use a aperture ring to set them. So, you cannot stop down the lens and would have to use it wide open at all times.
IMO, don't waste your time or money on adapting C/Y manual lenses to a 20D. The focusing is close to impossible with the focussing screen of the 20D. Plus, the screen in the 20D is not interchangeable like it is on the 1D series digital cameras. I have a 20D and tried some C/Y glass on it ... so take my word for it.
I use a Canon split screen on the EOS 1D series cameras and it works fine.
IMO, don't waste your time or money on adapting C/Y manual lenses to a 20D. The focusing is close to impossible with the focussing screen of the 20D. Plus, the screen in the 20D is not interchangeable like it is on the 1D series digital cameras. I have a 20D and tried some C/Y glass on it ... so take my word for it.
I use a Canon split screen on the EOS 1D series cameras and it works fine.