stick to the camera

I have different objects in a render context, and move around in it with the
camera's position and lookat messages. My problem is, I want to be able to
make a specific object stick to the camera at a fixed position in the window
while moving the camera around the other objects. So basically I need to
calculate the position and rotation the object using the camera settings.
I'm obviously not very good with math cause it making my head hurt. Can
someone please get me on the right track? Thanks.

Thijs