I may be having difficulty in understanding what you are wanting the end result to be, and perhaps I view the term free-form differently than you. If you restrict something to a given degree of movement it is no longer free form in my mind.
When you are using the free-form tool and you wish to skew and object a given angle, you enter the desired angle and use the enter key or use the free-form cursor and left click anywhere in the frame. The "apply to duplicate" and "relative to object" option selections have no effect in this case as they do when using the free form-tool.
What is it you wish to accomplish? You may want to use the skew in the transformation docker.
Jack Ross at 11:39 (GMT -5) on Mon, Dec 27 2010]