I am trying to create an event handler that can add a property to a MediaType when it is created. I am using the v6 API and I can already do this with a ContentType using the ContentTypeService but I can't find a service for MediaType objects or any means of doing this via the MediaService.

I have tried putting break points on the MediaService and ContentTypeService to catch the saving of a MediaType but with no luck.

void MediaService_Saving(IMediaService sender, SaveEventArgs<IMedia> e)
{
     foreach (var item in e.SavedEntities)
     {
         return;
     }
}

Or:

void ContentTypeService_SavingContentType(IContentTypeService sender, 
                                          SaveEventArgs<IContentType> e)
{
    foreach (var item in e.SavedEntities)
    {
        var dataType = DataTypeService.GetDataTypeDefinitionById(-92);
        item.AddPropertyType(new PropertyType(dataType)
            {
                Alias = "alias here",
                Name = "name here",
            });
    }
}

Where should I be looking? It's not obvious how to manipulate a MediaType from here.