Found a product called "Marine Tuf-Cloth." According to my sources, this should be the stuff.
I cleaned the mill idler, and head pulley. I got rid of all the rust, and put the stuff on. Weather today started cool and rainy, then proceeded to clear and warm. If I'm in the garage on a day like this, I can watch the rust form on unprotected iron. So far, the pulley looks pretty good. I ran the mill just to see if there is any slip, and it seems to be working great.
I'll update if anything changes.