Open comment in a popup window

[aleams]

Hi,
When my user read a news in the portal and want to make a comment out of it, I want that if he/she click the comment the popup window open rather than the user is send to the forum (containing the news) to make a comment.

The idea is that when user read several news, it is not comfortable to go back and forth between portal and forum to read and create comments out of it. I also don't wan the user acces the forum containing this news (I prefer the forum is to be hidden and the user can only read the news from the portal)

Have any body done this before? Any idea how to do this?
Thanks