I'm not an electrician so don't take my word as gospel but this is how I did Lee_H's.
Get the two red wires and twist them both together, then do the same to the two black wires.
You then need to locate your sidelight wires which is easy enough. Find the positive wire, cut it, expose the wires and solder into a sort of T shape making sure the old circuit is back connected but the red wires are also attached.
Do the same for the black side and it should work.
Make sure you use plenty of electric tape to cover up all exposed wires.
Here is a crap diagram to try and make some sense of it for you.