One of the route options is to use Preferred Roads. This tells MapPoint to calculate routes that use your route preferences. Unfortunately MapPoint's road preference settings are reset for every route, so you have to set them explicitly within MileCharter. Do this by using the Road Preferences dialog box.
When the route type is set to Preferred Roads, the Preferences button to the right will be enabled. Press this button, and you will be presented with the Road Preferences dialog box:
Each road type has a slider that specifies your preference for this road type. Note: the names and number of road types varies between the North American and European editions of MapPoint (the above screen shot is taken from MileCharter running in MapPoint Europe).
Slide each slide to your preference from Dislike to Like. The default is a mid-point of "no preference". Press the Reset button to resent all sliders to their default central positions.
Press OK when you have finished setting the road preferences.