I notice your mail in the discussion list also, So far, I think SGuy Ge's anwser is helpful. here quote his reply:
You’ll need to write a VS package for that purpose. Please take a look at the
State Machine release on CodePlex as an example, it includes
such a VS package.
Be noted that it works a bit differently than you might have expected, i.e. the toolbox items are not installed during installation time,
rather, it’s installed when the package is being loaded. But it’s closest to what you want.
Hope it would be helpful to others