Routing in Mapsource


I have a Nuvi 750 on order and am anticipating its delivery in October or November. In preparation, I am trying to creat a route of a vacation I will be taking in Mexico next January.

I purchased a gps map of Mexico from the following link: The Mexico map has been installed on my PC and I can see it in Mapsource. The map is pretty detailed but I have found some problems primarily with roads that are missing from the map.

I need some help in making the route travel where I want it to go when there is no connector road between two waypoints I created. I know the road is there as I can see it on Google Earth.

How can I get the route to cross that gap where I know a road exists, but is not on the Mexico Map contained in Mapsource? Can I tell Mapsource to route cross-country as it does not know a road is there?

Thanks in advance for your help. I have learned a lot from reading this forum.