When I melted the wiring for my glow plugs I opted to get a used harness. I took the chance and spliced some length of wire to the wiring for the engine sensors and starter. That way I could wrap it all up in split loom and "tuck" it. I just routed it in such a way that it was not near the hottest engine components and out of sight. By tearing my old harness apart I was able to splice the harness with the same color and size wires as in the schematics. 

If you do this you should get a used engine harness to source for wires. YouŽll probably have some left over to use when you add some wiring to your dash or something. Then you have black and white grounds, green wires for parking light related things and so on.