It ought to be fairly easy to do this, but you'll need to dig into your wiring.
To trigger fogs from parking lights, find the foglight relay and change the wiring so the trigger line comes from the parking lights instead of the lowbeams.
The trick now is to make them go off when the highbeams come on. Get a normally-closed relay (usual sort is normally-open) and wire it so the trigger line for the fog light relay runs through the normally-closed relay and the normally-closed relay is triggered by the highbeams.
The resulting setup should work; when the highbeams are off, the NC relay will pass current through and the fogs will come on with the parking lights. When the highbeams switch on, the NC relay will open the circuit betweent the parking lights and the foglight relay and the fogs will switch off.
As to where to find the appropriate connections, someone else will have to help. I have not done this myself and am speaking generally as to how to make this happen.
If you do it, definitely do pics and document it as I'm sure others would be interested.