These LED lamps are a direct fit, no mods necessary on the bumper itself. Regarding wiring, they can be wired to work 2-way just like OE tail lamps where you can use the (+) signal of the parking lights to have them on at the same time and the second (+) wire from these lamps connected to either the brake lamp signal or turn signal wire. When wired this way, it'll be dimly lit and only light up brighter when the second signal is triggered.
As to how I wired it for now, I wanted it to be similar to a rear fog light and didn't want it dimly lit. I didn't use the signal wire on the LED lamps for the parking lights; instead, I just used the second signal wire, which triggers the LEDs to light up brighter as pictured.
The tow hitch cover actually has a diagram as to what correlates to each pin so finding the (+) signal was very easy.
What I meant by wiring them up separately later on, is using a relayed wiring harness and switch so I could turn them on without having to wait for the parking/headlights to turn on since I keep it on AUTO at the stalk.
"I may think I have inalienable rights to be alive and happy but I don't - life is a blessing."
- Terrence McNally