Files to look at:
How To: Implement a Custom Route Provider
This example demonstrates how create a custom route provider and use it to calculate a route between two geographical points.
To do this, design a class inheriting the InformationDataProviderBase abstract class and implement its CreateData() method. Then, design a class inheriting the IInformationData interface and override its OnDataResponse event. Implement the CalculateRouteCore method to provide custom route calculations.