I did mine differently, but I had to build my own wiring harness for the foglights. This is more trouble than it is worth for most folks. I left all the wiring on the stock light switches in place and used the foglight wiring to power the relay coil. The other side of the relay coil is connected to ground. I have an inline fuse that picks up power from the battery side of the starter solenoid. It is connected to the relay contact. The other relay contact is connected to the new wiring harness I made for the foglights.
The advantage of making your own foglight wiring harness is that you can run 100 watt foglight bulbs. The stock wiring harness will not use 100 watt bulbs without overloading and causing a fire.
Unless you are good at electrical wiring, have the skills and tools (crimp tool, soldering gun, heat gun for the heat shrink tubing, etc.) I recommend that you stick with the Corral method.