I believe the battery hot cable runs to the hot side of the starter solenoid in the engine bay. There is a large hot red wire connected there that runs back into the passenger compartment and connects to one side of the ammeter. The other side of the ammeter then runs back to the Alternator as MJ already said. I would simply bolt them together and wrap them well.
The wiring diagrams are out there on The Pantera Place I believe.