If you have an actual part, you could digitize it with a CMM.
Normally it is done through measuring the part and re-creating it in CAM.
Best CAD/CAM would be whatever works best for you. I might tell you MasterCam and then you try it and say it is too expensive. I might say GibbsCam and you might try it an say you hate the drawing interface. Best thing is download as many trial versions as you can and try them out and find which works best for you.