private void initKeys() {
    /* You can map one or several inputs to one named mapping. */
    inputManager.addMapping("Pause",  new KeyTrigger(KeyInput.KEY_P));
    inputManager.addMapping("Left",   new KeyTrigger(KeyInput.KEY_J));
    inputManager.addMapping("Right",  new KeyTrigger(KeyInput.KEY_K));
    inputManager.addMapping("Rotate", new KeyTrigger(KeyInput.KEY_SPACE), // spacebar!
                                      new MouseButtonTrigger(MouseInput.BUTTON_LEFT) );        // left click!
    /* Add the named mappings to the action listeners. */
    inputManager.addListener(actionListener,"Pause");
    inputManager.addListener(analogListener,"Left", "Right", "Rotate");
  }
Custom Keybinding: Map named actions to inputs.
jme3-examples/src/main/java/jme3test/helloworld/HelloInput.java