Aim helper for pool example?

Hello,
I am trying to add a “guide” line to the pool game example. Basically, I want there to be a line pointing to the direction in which the ball is going to go. How could I go about doing this? I attached an image to show what I mean.

http://i51.tinypic.com/1678h87.jpg

The red line is essentially what I am trying to create.

Thanks in advance [import]uid: 23697 topic_id: 10838 reply_id: 310838[/import]