Okay, Chani has been pushing me to share this. I've been reluctant because I didn't want everyone to know my secrets.
Anyway, I have attached a pic showing my method. I will try to talk it out to make sense.
The wireframe view is showing the two colors of vinyl as they would look after being cut and weeded. The filled image is the same thing, just showing the colors. You cut and weed the first(bottom) layer as mormal. But, for the second layer, you ALSO cut the first layer(outline).
This gives you the outer edge of the first layer on your second layer. This will allow you to line up the second layer perfectly with the previously applied first layer. You leave the second layer vinyl(around the outside edge) to give you your first layer edges. I know this is probably not the best explanation, but if you study the pics, hopefully it will make sense.