You don't touch the stock wiring. Leave it alone. You just ADD 3 new wires. You do not rewire the engine.2 of the wires are stupid simple. Make new ground wires for the engine block to chassis and battery negative to chassis. You don't remove the stock ones, you just add new ones.
The third wire goes from the Alternator positive output to the battery positive. The only part that is a hassle is sometimes it's difficult to attach a new cable to the alternator positive terminal.
Really it's pretty simple.