Get some clean paper towel and gently press it along all of the edges of the rocker cover to see if there's any fresh oil somewhere, that should tell you where the oil is coming from. Also get under the car and check the pipes to the intercooler in the same manor to see if there's wet oil from the boost pipes.
I had an oil leak in the Golf R when I bought it, was told it was possible the transfer box but turned out to be a breather pipe at the back of the cylinder head, which connected to the rocker cover.
Hope you get this sorted mate, don't like the idea the old girl is causing you problems!