Howto add feature checkbox to a light?

Hi there! I’m relatively new to Home Assistant and run Hassbian 0.75.2 on a Raspberry Pi. Currently, I’m involved in some development for the ESPixelStick, a DMX LED Strip controller that can also be controlled via mqtt_json.

I have a few set up and they work just fine using this type of entry in configuration.yaml:

  - platform: mqtt_json
    name: "esps2"
    state_topic: "esps/2"
    command_topic: "esps/2/set"
    brightness: true
    rgb: true
    effect: true
      - Solid
      - Blink
      - Flash
      - Chase
      - Rainbow
      - Fire flicker
      - Lightning
      - Breathe

Now, most of the effects can be mirrored (start from center) and/or reversed (run the other way round). When clicking on the light, I get a nice popup with a switch, brightness, color and effect controls, but I would also need two checkboxes in there for [x] Mirror and [x] Reverse.

These, in turn, should generate something like "mirror":true and "reverse":true in the MQTT JSON string.

Later on, we might also need a speed slider (default: 1000), but this is not currently implemented.

I can’t find out how to do this, do you have any tips for me?
Thanks in advance!