Journey to robust windows services: debugging your WiX custom actions

I've recently had some trouble getting WiX custom actions to work, and after searching around for a while, I found this article. It gives the reader two options for how to debug WiX custom actions, but I had to use both in combination to get it to work. I'll repeat the steps here, just in case the link goes stale:

1. Follow all the necessary steps to create a WiX setup project, along with a separate Custom Action project (available as a project type in the New Project dialog in Visual Studio 2010+ with WiX 3.7)
2. After you've created your custom action method and gotten the project building, add System.Diagnostics.Debugger.Launch(); at the beginning of your custom action method. This will kick the custom action into the debugger so that you can debug it (assuming you've got the wixpdb in the same directory from which you launched the installer).
3. Go to Control Panel -> System -> Advanced System Settings -> Advanced (tab) -> Environment Settings (button) -> System Variables (group) -> New .... (button) 
4. In the dialog that comes up, create a new variable called 'MMsiBreak' (without the quotes) and give it the value of your custom action method (e.g. MyCustomActionMethod)
5. Now run the debug version of your installer and it should get kicked right into your method and allow you to debug your custom action.