Last week you had a caller that was wanting to replace his carpeted stairway with hardwood. You did not have any really good ideas of how to do this.
One of the advertizers in Fine Homebuilding magazine is Young (youngmanufacturing.com). They have a product called young RetroTread. They say "makes it easy to renovate any carpteted stairway to premium hardwood." This sounds like just the product that your caller was looking for.