Take several pieces about 4" to 6" long just below a node (leaf joint), then remove most of the leaves except at the tip. If you can get hold of a sheet of polystyrene, cut it to fit a dish like an old ice cream carton which you fill with water. Float the polystyrene on the water and pierce it with several holes so that you can push your cuttings through. They should make roots in a few months.

In my experience, it works best if the pieces are between pencil thickness, and little finger thickness.