Hi Umberto:
I don't think is implemented in GSX yet, but it sounds interesting to add the feature of towing an aircraft from one gate to any other required place of your airport and driving the truck by yourself using your joystick and a realistic groundspeed.
Another developer claims having released a pushback add-on with that towing feature that would work with MSFS, FSX and P3D, but I would prefer to see the feature in GSX, more professionally developed.
Cheers, Ed