Having gotten my flash and PC sync cord, I decided to modify it to use 3.5mm audio cords, of which I already had a couple of meters extension.
First of all cutting open the PC sync, finding two separate cords.
Then peeling those and fitting into the 3.5mm stereo females. Didn't know the "official" way to connect, but I knew that as long as connect the same cables to the same connectors I'd be good to go.
No pics from the soldering process since it's hard to hold a camera in your mouth.
Then the cover screwed on. The little pieces of white seen are pieces of adhesive tape I put to cover the sleeve connector (tip, ring, sleeve); I had accidentally left too much cable uncovered and was afraid it could short out if it touched the sleeve.
Now to test it out...
It works! Holding the cable.