There are a couple of active threads on this. I have been trying to pinpoint my leak for about a month. I tightened a couple of bolts on my valve cover gasket last week and the smoke has subsided a little but the smell is still there - im hoping its just burning excess oil at this point.
You should check:
Pass CV boots
Oil return line on base of turbo
Coolant lines on turbo
Oil lines on turbo
There are a couple of other seals to check, but I cant remember what they are.