Amazon Echo Skill--Support for AudioVolume Capability via Alexa StepSpeaker Interface?

An Alexa smart home skill can implement a "StepSpeaker" interface:

[Alexa.StepSpeaker Interface | Alexa Skills Kit](https://Alexa.StepSpeaker Interface)

I use it in code running on an AWS lambda server to forward AdjustVolume, and SetMute directives to code running locally. That code sends IR commands to "dumb" audio/video devices making them "smart". :grinning:

Is there a way to advertise a StepSpeaker AlexaInterface so Alexa can invoke volumeUp, volumeDown and a mute(bool) methods in a custom driver that has declared an AudioVolume capability?

If not, any plans to do this?