The shell fits rather tightly on this model and the best way I have found to remove them is to pry the shell up from the tab located under the rear of the cab on each side with a jewelers screwdriver.
This installation is going to be similar to the others using the CN or CN-GP decoders. If I seem to skip over something or something is not clear I suggest also checking the other posts that use these decoders. After getting the shell off I fully dis-assemble the mechanism. This is necessary because the decoder wires are going to need to be connected to the motor. When removing the motor, I always mark the top to keep the polarity correct.
A pinched wire may not show up for quite some time until the insulation breaks down and the conductor comes in contact with the frame.
At this point I will apply the output of a DC throttle to the orange and gray wires and check how the motor is running before proceeding with the final steps.