Well, I am finally getting around to posting the rest of my experience. Here goes…
This is what the doll looks like:
First thing was to remove the cover in order to expose the circuitry. The body had several screws in the back. Once removed, the body split in half vertically. At that point - the arms and legs could be removed. Here is a picture:
The 1/8 Mono Phone Jack came from Radio Shack Catalog #: 274-333. Here it is shown taken apart with the wires already soldered to it. Also shown is the proper size drill bit for making the hole in the doll. The drill bit needs to be the same size as the housing that provides shielding.
Once you have determined where the plug will be installed, drill the hole using the proper size drill bit. Think about the location before drilling the hole. Will the jack hit anything inside the toy once installed? Take into consideration the plug sticking out that connects it to the switch. Visualize making sure once everything is hooked up that the cord will be at an angle that won’t interfere with the operation of the toy. Also, once you’re ready to go, be sure not to drill into anything inside of the toy, or go through the front accidentally.
Once you have the jack installed, screw the nut on the inside that secures the jack to the toy. This toy was exceptionally easy to figure out where to put the wires. The doll had a switch in each hand with two wires coming from each hand. One wire from each side was soldered to one point on the board with the other wire from each side connecting to a different point on the circuit board. The wires that attached from the plug were just soldered to the same two places on the circuit board. The end result is both hand switches still works like normal, along with the third when an external switch is connected.
Here are a couple of pictures after everything has been re-installed.
Here is the video showing the switch in action. The first part shows the original functionality that was maintained (by just sqeezing the dolls hand) and then using the doll with the switch.