Most sync cords do not use wire, but a flexable metalic ribbon. Very difficult to solder or do much else with it. With some light wire, wrap a loop around each sync post on the shutter (insulated is best), then insert one of the wires into the center of the PC fitting . still keeping the two wires seperated wrap the second wire around the silver ground portion (ground) of the PC cord. Gaffer tape the whole assembly to the cord so it does not pull the center wire out of the fitting. Not the prettiest hook up you will ever see, but It will work!
Charlie