Unfortunately CameraCaptureTask doesn't have Height and Width properties, so you cannot crop the image right after it is taken. You can do two things:
1 - (I don't prefer this one!) Allow the user to take a picture using the CamerCaptureTask and then after it is completed, call the PhotoChoserTask so that the user again chooses the clicked image. Using this option you can crop the image using the Height and Width properties of the PhotoChoserTask
2 - Use Nokia Imaging SDK to crop the image. This SDK has many filters including the Crop filter which can be used to crop images. It is not as easy the PhotoChoserTask crop but you can still crop the image. There is sample code to crop an image on this page. Check it out!
Hope this helps!