It depends what part of your turbo is cracked but a crack on the housing (most common) will not in anyway result in burning oil at all. Valve stem seal failure on 20vt engines are very common at your mileage. Typically it's worse when you have excessive vacuum such as when you go down a hill and your off the accelerator and in gear, this vacuum draws the oil through the valve guides where it collects until your back on the throttle again such as when your at the bottom of the hill where it will be burnt and give a blue smoke. It's not quite as you describe where oil will simply pour through your valve stem seals when your engine is off like a tap left running. When your engine is running on idle or downhill with the throttle closed this vacuum draws the oil through.
Try to get to the bottom of it, if it turns out to be your valve stem seals then chances are the majority of machine shops won't touch 20vt valve stem seals (and 2.7tt) because they are much smaller and they won't carry the removal tool needed, if that's the case you can just strip the head and send it to me and I'll remove them and fit your new ones for £4 per valve stem seal.
