you might have amperage problems, but find the wires that go to the front running lights. Split the wire, and run one split back to the toggle on the dash, replacing the incoming wire (which goes with the headlights) with the running-light wire. (you should be able to find the running light wire under the dash, a volt meter would make it easy). After that, whenever running lights are on, you would be able to toggle fogs. However, since I dont have my fuse list nor wiring diagram in front of me, you may blow a fuse doing this. But hey, give it a shot, if you blow one, just wire it back!
Beware, back-current from a blow on something as high-wattage as bulbs could trigger something else. But you should be fine. Often neons are wired to run with running lights, but they have a separate power source.