From what I understand to link the model to the livery, you need to create a subfolder in the Airnav GE_Models folder that matches the four letter ICAO type designator code in database explorer, if one doesn't already exist. Inside that sub folder you then add the livery file named for the three letter ICAO Airline code.
So for example if you wished to make Cargolux and British Airways World Cargo Boeing 747-8F model and livery. You would create the new model and create a new folder in Airnav Radarbox/GE_Models called B748 - In that subfolder you would place your B748.mod model file. Then you would create additional sub-folders in the Airnav Radarbox/GE_Models/B748 folder called CLX, BAW (whatever the callsign they regularly use, so for example the Global Supply Systems B748 routinely use BAW flight numbers as a callsign) and in these airline folders you would put the texture.liv files for each respective airline.