As you may have found, to the bane of all developers, there is no QueryTerritories() method in the API.

Fortunately for you, your territories are state-boundary based, and there are freely-available SHP files for state boundaries at the US Census site. You can use the MapPoint Spatial Data Import Utility to import the shape file, then use the MapPoint QueryShape() method to return all pushpins within a particular shape.

Links:

Spatial Data Import Utility:
Download details: MapPoint Spatial Data Import COM Add-in

Census Bureau State Boundary SHP file:
http://www.census.gov/geo/cob/bdy/st...99_d00_shp.zip


HTH
-Paul