This installation is for the N Scale Kato RS2. It uses the TCS K2D4 Decoder - performed by TCS.
The picture above shows the Kato RS2 with its shell on.
This picture shows the locomotive's chassis with its shell taken off and the original lighting board.
Next slide and lift out the original lighting board so that your locomotive looks like the image above.
Apply Kapton tape (as shown above) over the frame above the motor tabs and at the rear of the chassis to prevent the decoder from shorting against the frame.
Next carefully spread the copper tabs so that they fit over the chassis as shown in the picture above.
Carefully slide the decoder down while making sure that the copper tabs remain aligned as show in the picture above.
Slide the decoder back until it sits in the notches in the frame. Be sure that the motor clips on the decoder completely cover the motor tabs on the locomotive.
You can now replace the shell and run your locomotive!