Assumiong you have the loom with the light, it's easy! It literally plugs in to the existing plug behind the panel! Really couldn't be easier.
Take yourself to a scrapyard, find a Golf with a boot light. All you need are: the pin switch, just unscrews and pulls out. Then you need the two wires coming from the back of the light, which go along to the switch, and then to a two pin connector. Then, go home, cut a hole in the shelf for the switch (unless its there already) and plug the connector into the connetor thats already there. When you get the loom from the scrap car, have a look at the plug, so you recognise it on your car!!
MAke sense???