I hope I am not out of line to explain this...
First off you have to create a new Swatch (make it a bizarre color, something that you probably won’t use for any thing else... I made a crazy Pink!) . Name this swatch “CutContour” make sure you use these capital “C’s”. Color Type must be “Spot Color”, and I use “CYMK” for Color Mode.
Now choose the vector line you want to cut and choose this CutContour color you just made. Make sure to save this file as EPS. Now open this file in your cutting plotters driver and it should recognize this line to cut and anything else to print if you have a printing/cutting plotter.
HTH