TerraScan Trajectories- Adjust to Geoid

Hey guys, I'm fairly new to the processing of trajectories and am trying to figure out how to adjust a trajectory file to the Geoid12A model using TerraScan. Specifically, I'm hung up on using the intg.exe program downloaded from the NOAA website. It's asking me to input XY coordinates, from which it will interpolate the dZ correction at that location. From the GeoCue website it sounds like I need to extract a sub-grid using the associated xntg.exe program, which I have done and it seems to have worked, however I'm not sure what I'm supposed to do with this file as it just contains dZ values. I've been banging my head against the wall trying to figure out how to get an XYdZ file to no avail. Any help would be appreciated.