I don't think it will meter will it? I don't *think* it's a CPU lens (ie has the electrical contacts on the mount) for the lens to tell the body what it is, and the D40 hasn't got the menu function to input manual lens data, so afaik, you'd not only have to focus manually, you'd also need to set the aperture and shutter speed manually too, as the body won't set them for you.
probably more trouble than it's worth but then again, it's the way people used to take photos!
dave