Enco I believe sells Kasenite, and will ship it to you. I found this recipe, but not sure about finding the ingredients:
Pulverize equal weights of saltpeter, prussiate of potash, and sal-ammoniac and mix together. Prepare a dipping solution by adding to each quart of cold water 1 0z. prussiate of potash and 1/2 oz. sal-ammoniac. Heat steel to red hot, roll in the powder, then plunge into the liquid.
Also, look for Hard n Tuff. I was able to get it through a welding supplier.
It's all about increasing the carbon content of the steel. I believe you could get some additional carbon by heating the steel red, then packing it in a charcoal can, or similar. Probably would take a couple of shots. Need to experiment.