The NuGet package uses MSBuild events to hook into the build pipeline and:
It embeds the satellite assemblies into themain assembly as resources after the main compile step as per Jeffrey Richters example.
It then uses Cecil to add/edit the module initializer which will call the hooking code to load the satellite assemblies from resources.
The module initializer will run once the assembly is loaded. It will hook up the required events. See the Injected code.