does anybody know which wires to use for fitting the illuminated door sills?

 

You have to test them using a voltmeter. Wire once into the return from the door switch. This wire is easy to find. You'll see where it comes out at the bottom-rear of the door. Then find a wire (of similar size) with a constant power supply and tap into that. I used 3M connectors and they worked great! Keep in mind these will only work if the wires are of similar size.

It's hard to give a color because there are many wires that use the same color. Good luck!