Ecamm Live supports streaming to Wowza Streaming Cloud using the Custom RTMP feature. When creating a stream, use the settings shown below. Then, in Ecamm Live, pick Custom Stream Key from the Destination menu in the bottom right-hand corner of the screen. Enter in the Primary Server for Server URL and the Stream Name for the Stream Key.

Also, be sure to click the green Start Live Stream button to start the stream on the Wowza website before starting the stream in Ecamm Live.