Thanks to Jean, a.k.a. "jano", there is now a nasal script included in DavePack that allows JSBSim models to properly refuel. All the F-4 models have been updated to use this. I also moved the upper mirror in each F-4, flipping it to a stowed position, to give a better forward view. In order to refuel the following conditions must be met:
1) The refueling system must be activated, and the probe (or door) must be in the extended (or open) position.
2) You must be refueling from a tanker which has a matching type of connection; either "probe" or "boom" type.
3) You must be in "the box" behind the tanker.
When conditions are met you will start taking on fuel, and a small green light will illuminate on the fuel gauge. Fuel will go in to all tanks at an equal rate. If the fuel gauge only shows tank[0] quantity, then the tank[0] quantity will increase slowly until the other tanks are full.
The download rate is 6000 lb/min, which is hard-coded in JSBSim.