Well, see Adobe Illustrator and Inkscape are vector based illustration software programs. You can draw lines and then scale them and they stay the same thickness but grow or shrink and maintain proper proportions. They have rulers which you can click and drag away from and then will draw a guide you can snap to.
So, if your had your template on a grid, you can set an arbitrary 0,0(upper left or lower left would be normal starting places), this is where you start all your measurements from. Then you just plot points on the curves/lines of your templates and measure with a ruler from 0,0 to the point. So for the first point on your first line, say it is at 1 inch down and 2 inches to the right on the graph paper. In whatever program you choose, you put two guides down, one at 1 inch on the vertical axis and one at 2 inches on the horizontal axis. You measure again for the next point(or just do them all and write the values next to the point, then start putting them in). Now you have two sets of intersecting guides in the software and you can draw a line between them. Whenever there are too many guides and you start losing which intersection you are one, just delete the guides and start over.
If your are still confused, let me know and I will try to put together some kind of set of images or a video.
