You can always just use a soldering iron to loosen the solder right under the light, pull the light out and solder two wires in its place, without hacking up the ribbon.
If you don't want to do that and can't trace the wires with your eyes, you can use a continuity checker to see which wire is which by trial and error. Using your eyes, you should be able to narrow it down quickly.
Also, look at the motherboard where the ribbon normally connects. See if there are labels on it there. Most have labels indicating which pin is which.