I've looked through the source code before but I don't think I saw the CodeGenerator solution. That's a gold mine for the future.
The answer to my question is below. This LPT file is acting upon each entity in the project.
EntityMapping mapping = currentProject.GetGroupableModelElementMapping(currentEntity, _executingGenerator.DriverID) as EntityMapping;
Use the mapping in the comments for a generated class
Sample result in the generated file: