Both Bing and Google Maps have drawing tools that you can use to define an area for a technician. The tools behaving a little differently from each other, as well as with different browsers, but once you have drawn the shape, the Schedule will behave the same.

Using Bing Maps

Use the Bing Maps polygon drawing tool  located at the top left of the Map View to draw a shape on the map. 

Adding a shape

1. Choose the resource by clicking the Select Resource for Routing drop-down and selecting the technician.
2. Click the drawing tool and then click once on the map to set the first point on your shape.
3. You now have a line that will follow your mouse on the map.
4. Click another location on the map to view a straight line. 
5. As you move your mouse a shape appears on the map.
6. Click on the map again with your mouse to create an endpoint. 
7. You can add as many endpoints again to set another point. 
8. Repeat step 3 to add as many points as you'd like by clicking in other areas on the map.On the final endpoint, double-click with your mouse.
9. After clicking the final point, press the ESC key on your keyboard to be prompted to add the unscheduled appointments to the technician's route. Appointments that are already scheduled are not added to the list.
10. You can edit the technician's route by dragging the appointments or by using the icons at the top of the route list. See Viewing and optimizing routes.

Editing a shape

The shape that you've created can be edited by clicking and dragging the circles (or handles) that display on each corner and mid-line of the shape.

...