The other way you could do this if you have polygons that represent your MSAG areas is to use the IntersectFeature method. This method will intersect the polygon features you have and populate the attributes you specify. We use this method in the Address Data Management map now to populate the Place Name, USNG, etc.
If you don't have polygons for the MSAG areas and still need to troubleshoot the SIDE method, please contact Esri Support Services. They can help you nail down the specific issues you are having with your configuration.
Scott