Google Maps Api Custom Routes

Hello, Okay so i have a simple google maps integration that maps two lat/long points between each other. The problem is that im doing this for my university which has many buildings within one campus. Google Maps can see these buildings but it cannot show me the internal paths from each building. Hence when i use the map to generate a route from one building to another, instead of the routing going straigtht from one building to another it is looking for the nearest "road" and then using that as a path to go the other building. Example : [login to view URL] check the two radio buttons and click submit On the maps page, zoom in abit and you will see each building including "levermore" and "social works". However i need somehow to mark the internal path between the buildings so that google uses this custom path instead of the current path. thanks! naq