Mike

EDIT: This only seems to work for audio, thanks for pointing it out

Try the AirCast community addon. The description says:

AirPlay capabilities for your Chromecast players. Apple devices use AirPlay to send audio to other devices, but this is not compatible with Google’s Chromecast. This add-on tries to solve this compatibility gap. It detects Chromecast players in your network and creates virtual AirPlay devices for each of them. It acts as a bridge between the AirPlay client and the real Chromecast player.

Sounds like just the thing you want, although I haven’t tried it personally.

I only have Zigbee devices so far, but I’m running it in multiprotocol mode. No problems so far.