Hmmm. I think in the INPUTS for the camera or the curve you should be able to see two values. Both of them control where the camera is looking. All you should have to do is keyframe these values correctly as the camera goes around the curve.

For instance, at frame 5 look through the camera then alter the values to make it look at the object you want, then select the values in the INPUTS in the channel box and keyframe them, then go to frame 10 and do the same thing. Maya will transition inbetween frames 5 and 10 as usual.