Hi Tracey,
The only error I see in your code is that you are not assigning a pageid for the module so it will not appear on any page.
I really don't want to forbid you from doing this kind of thing, but I'm not wild about it. I think features should be self contained and not really depend on or orchestrate other features, so I would not be drawn to doing this kind of thing myself, but if it meets your goal and at least your custom code is separate from mojo code then I guess it is ok. But this is not a way the Html module is expected to be used from my point of view.
Best,
Joe