While you cannot print directly on leather from a printer, you can still create a printed message on the leather. By the way this also work on other non-paper items, like wood.
"Blender" pen from an art store.
Smooth Leather or Vegatable tanned leather or other solid object
Step 1: Print and Cut
Print your message on a laser printer. Inkjet will not work. When printing be sure to mirror the image, so that it prints backwards.
Cut the words or picture out and leaving enough space around the side to hold onto the paper firmly.
Step 2: Use Blender Pen
Turn the paper over and place on the leather, being sure to align it properly. Once you use the blender pen, it is permanent. Run the blender pen over the paper pressing moderately hard so that it soaks through the paper. Hold firmly onto the paper so that it does not wander. Once the blender fluid reaches the ink on the back of the paper it liquefies and transfers to the leather.
Step 3: Transfer Image to Leather
Lift the paper off carefully. The leather will be damp with the fluid. It will dry as if it was never there. Now you have a printed image on the leather!