let me try to give a more direct answer to the OP's question, than my first response
yes you can substitute cake flour for all purpose flour in a cookie recipe. In fact, cake flour is a more appropriate flour to use than all purpose in baking cookies
when i substitute cake flour for all purpose flour in a recipe for cookies, or any recipe calling for all purpose flour, i use 1 cup and 1 T. cake flour for each cup of all purpose called for.
I agree with suzie, you can't go wrong with using cake flour for cookies, just add 1 T. extra flour per cup of flour in the recipe.
I have had no disasters in the 35 years I have been baking with cake flour, whole wheat cake flour at that.