how to make the u3d window as a childwindow in exist window?

Unity Engine
1

as the title said.
i want to push the u3d window into a exist window.
but i rather push a exe file into the exist program than use the webplayer way.
is someone use the u3d this way?
please help me. thank you very much.

2

does someone use u3d the same way? please help