Visual Studio & TFS: How to add a custom tab on Check In

Hi,

I want to write a custom Plugin for the "Check In" window in VS.
It should be a new point in in the list and replace the view on the right. To make it more clear I've attached an image.

I don't want do write a new policy and the Check-in notes are not customizable enough for me, I've already looked into that.

Any help is appreciated
Thanks!
Simon