you need one of two things -
1) a 'camera and aim' (or 'camera, aim, and up') type of camera. I believe these can be created through the normal dialogue. One nice thing about them is that they also automatically focus the camera at the designated point. You would then have to parent the aim to the object, but that's not so bad.
2) create an aim constraint for the camera to point at. While similar, this is not identical to the above option (I don't think it includes the autofocus bit). And if you're not careful, you can have issues with which way the system thinks is 'up'. However, its fairly trivial to set up, so.... Just add the aim constraint between them like any other two objects