Google Maps Driving Directions, change Stroke Color?

I have something very similar to this example:

All I am trying to do it change the stroke of the line from one city to another city, which is currently a purple color?

I tried putting strokeColor in myOptions, but no luck:

      var myOptions = {
        zoom:1,
        strokeColor: "#000000",
        mapTypeId: google.maps.MapTypeId.ROADMAP
      }

Solution

It doesn't look like that's supported without drawing your own line.