1. Make the IR blaster device as explained in the last post.
2. Program it using the sketch in my Bitbucket repository. You will have to modify the WiFi SSID and password variables.
3. Set up your home router so that your IR blasting server is hosted on a port other than 80.
4. Sign up for an AWS account and create an AWS Lambda function to control your speakers. The Lambda code is also in my repository; you will have to modify the host and port variables. Use "Alexa Skills Kit" as the event source. Note the ARN of the lambda that you create.
5. Set up an Alexa skill using the Alexa Skills Getting Started Guide. Creating your own Alexa skill requires many steps. If you follow the getting started guide, you will set up an example skill. You can replace the intents and hints from the example with those hosted in my git repository. Then, use the Lambda ARN as the skill endpoint.
Note that this project is terribly insecure. If someone knew my home IP address, they could very easily gain control over my speakers. The ESP8266 is currently limited in that it does not support TLS when hosting a server. If TLS were supported, the device could use a secret password only known to the Lambda invoking the function. But without TLS, that password would be transmitted publicly. Until secure servers are supported on the ESP8266, I can't recommend this project for anything serious.