@ChadForrester. Here you go.
This is just to show how I’ve got the speed sensor, power and LED wires routed. I painted my dewalt just for the heck of it. 
Here is an overall view of the sensor placement inside the DWP6111. I removed the speed control circuit rather than modify it. It is pretty straightforward, and I tool plenty of pictures in case I want to put it back together. I did have to add the blue insulated splice. The black and red wires are coming from the LED circuit. As far as I can tell, this is just two white LEDs in series. I’m running them with 9V DC from my main control box via a switch and a 150 ohm resistor.
Here is a more detailed view of the sensor placement. I painted one half of the DWP611 spindle with white-out as per the Super PID instructions.
Here is my main control box. I’ve got more switches than necessary, but I like to have lots of switches. Most of the switches are self explanatory, except the open-close. This allows you to switch off the closed-loop speed control for trouble shooting. Not really needed, as a switch, but again I like lots of switches.
Here is a view inside the control box. It is a little messy, but seems pretty solid. I hacksawed a piece of aluminum for the heatsink and added a ribbed heatsink I had in my junk box. I’ve got the 24V power supply supplying the grbl shield, the fan, and two adjustable DC-DC buck converters that I got off of amazon. One of them is supplying 5V to run the low voltage electronics of the Super PID, and the other is supplying 9V for the LEDs. Running all the DC electronics from the 24VDC supply assures that they all share a common ground, and that the grounds are connected in a a branching pattern so as to avoid loops. The PWM output of grbl shield is connected to the SuperPID so that the speed can be controlled via software. The only problem I’ve run into is that the lowest PWM output is interpreted by the SuperPID as 5000 rpm, rather than off. I’ve got a solution to that in the works.
Here is a closer view of the SuperPID wiring, showing the two DC-DC buck converters hot-glued to the side of the enclosure.
Hope that all helps. I highly recommend the Super PID. It is costly, but seems very well made. Also having true RPM feedback via the sensor provides better speed control at lower speeds than the current sensor based methods used by the built-in speed controllers.