I accomplished just that using the new stile guide.
What I did was setting the iframe expression into the screen of the info balloon widget.
"<iframe height='600' width='800' sr c='view.aspx'> </iframe>"
On that page parameter I made the query to get the file and ended up with the dowload tool just like we did before.
In the widget web block you must set the height parameter or you wont see anything coming :)
It worked for me.