Https can be enabled in WebMatrix 3 on Windows 8 with just a checkbox under "Settings." It assigns the first port in order for the first site, Port 44300 automatically. It also has pre-installed a self-signed certificate for local test development purposes in the installed base of IIS Express.
But when using WordPress / Php / Https plugin, the localhost port doesn't automatically switch over from the random port that localhost uses when in http mode. It actually removes the port number and gives a page error when going from a non-secure to a secure page.
Not sure where the problem is or if the plugin is doing something that affects this setup, but wanted to bring this up, as otherwise WEbMatrix is becoming a fantastic development tool for WP devs.