Yes you can set a control point key frame and then move a few frames down the time line and set another control point key frame and then move the control points that need to be moved. Keep doing that until you reach the end.
Motion can automatically rotoscope them for you so you only have to build a mask on one frame and Motion does the rest. I have a chapter that covers this in my Creative COW training DVD Moving with Motion which is on sale for 19.95. It regularly sells for $50. Best of luck.
Stephen Smith
Utah Video Productions
Check out my Motion Training DVD
Check out my Motion Tutorials