It's funny you should ask. I started making knives with hand tools and ended up buying a cheap bench grinder. I recently found what you're looking for in the catalogs of Koval Knife Supplies, (or something like that), and Texas Knifemakers Supply.
It's a Jet grinder attatchment and uses a 2" x 36" belt, available at either place. It costs about $150.00.
Both stores are easy to find on the internet.