In the original pedal design, there is a red LED in the middle of the housing to show when the pedal is getting power. If you want to retain that feature, you have to clip the original LED leads, and connect a wire to each one. Run those wires to a new LED (no resistor required here). I recommend using a socket of sorts on the end of your wires, so that you can change the LED easily if you install it backwards (it happens), or if you just want to try a different color.

In the photo, you can see that I used a yellow and a green wire for this, and simply left the original LED connected to one of the leads coming out of the PCB. I bent it out of the way, and soldered the new wire beneath it. (I told you I was lazy.) Note that this entire step is optional, since you might cut corners by using a switch that visibly indicates whether the power is on, as some DPDTs can.