Another way is to use your image uncut and simply move the image plane. Just map the file into the cameraShape image plane (under the Environment section) then manipulate the image plane's x,y,z coordinates to line them all up. Creating a cube helps with this. I leave the cube in the center then move the image planes in the order: top, front, side. The cube should outline the verymost portions of each view. This way you don't have to worry about one view being huge compared to another with photoshoped pieces.

The other method is also just as good. Just make sure that your image plane scale attributes are compatible with each other.

I'm not sure if that came out like I was hoping. PM me if you have trouble.