What your doing now is engraving, or using an outline, or contour toolpath. What your wanting to do (if I understand correctly) is called pocketing. I am unaware of any method for doing this without the use of a cam software. Your next question will be "where do I get this cam software?" There may be some free software that somebody can hopefully point you in the right direction to. Vectric software is highly respected, not free, but very cheap (compared to others). It would also take you well beyond pocketing, as your abilities grow.
http://www.vectric.com/Be forewarned that battles have been won and lost, and many lives paid in the argument and pursuit of the "best" cam software. I would rank it right up there with religion and politics.
Best of luck!