Journey to robust windows services: creating custom actions for your WiX installers

I've lately been trying to update my WiX installers to perform custom actions so that I can do some security configuration of my applications after they're installed. I got started with this article on CodeProject, but it was missing some information. Apparently, in addition to creating the separate project for the CustomAction DLL, you need to include as part of that assembly a CustomAction.config file with the following contents:

xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup useLegacyV2RuntimeActivationPolicy="true">
        <supportedRuntime version="v2.0" />
        <supportedRuntime version="v3.5" />
        <supportedRuntime version="v4.0" />
    </startup>
</configuration>

But what really got the thing working was targeting the CustomAction DLL to .NET framework v3.5, rather than 4.0 because I was getting some bad image format exceptions when trying to run it. Thankfully I found the MSDN article on enabling MSI logging. These two articles on stackoverflow.com also really helped out.