Right now, we only have Qantas as a vehicle livery for Australia, so it uses a "catch all" Y prefix, meaning all airports with the ICAO code for Australia will use Qantas ground vehicles.
If you could provide some list with actual handlers and their usual locations, we can add them to specific airports using a full 4 letter specification and/or the airline code assignment in AFCAD parkings.
You will also able to add your own logos and specify airports freely, as soon as we release the Paint Kit, which should be in a few days time.