Wish I wouldn't have included that splitter cable when I sold my Mogul. Tried to do the mod with the headphones that came with the TP because I still have the nicer set that came with the Mogul. Unfortunately, I couldn't get pin 4 out.
For those thinking of using the TP headphones for the cable, I wouldn't suggest it. It's got those weak headphone like wires in it. It doesn't have the nice insulated wires like in pzztgotbagz's pics. After opening it up, my plan was to use its one insulated wire (white) which should have been the Video + and the gold wire wrapped around it which I believe was the Video -. I was going to skip the audio all together.
For those interested, there's also a discussion on this topic over at XDA -
LINK