Greg, Dust in the viewfinder is sometimes on the underside of the focusing screen, pointing down toward the mirror. If so, it can be blown off easily--you may have already gotten rid of it. Just make sure you point the camera with the open lens mount area facing down, so that the dust doesn't fall down by the shutter blades or sensor. If the dust is on the top side of the focusing screen, there wouldn't be much you could do but remove the focusing screen and clean it.
Occasionally I have had dust on the mirror surface, which could be visible in the finder. The best way to get dust off the mirror is to use a blower. You can sweep the mirror with a very soft brush, but be careful not to put any pressure on it, and never use anything wet to clean it.
As Brian said, dust on the sensor would not be visible in the viewfinder, only in pictures.