Have you popped out the old CCV's and looked at them yet? That amount of oil seems indicative of those not doing their job properly; even if there was a lot of blow-by (and there will always be some amount), the job of the CCVs and the paths on the undersides of the valve covers is to get the majority of oil out of that air and back down into the pan (and to help regulate pressure, of course). Once those start to break, you'll definitely get more oil pushed (at idle) or sucked (above idle) into the intake manifold. Speaking of which, it's probably about time to do my CCV's.
I haven't read anything about anyone opening up the intake manifold, but it seems pretty simplistic. There is no gasket between the top and bottom halves listed on realoem.com, but I'm sure regular ol' gasket sealant would do just fine.
The VANOS solenoids control oil flow to the different sections of the VANOS units on the intake and exhaust cams (the gears on the front of the cams), making them twist to advance or retard the cams' timings dynamically.
Black 2007 Alpina B7
Tension strut bushings
White 2007 Alpina B7
Supercharger clutch/bearings, replaced exhaust valve/pulled head, sunroof seal, 6000K angel eyes
Black 2002 BMW 745Li (sold)
KW v3's, blue angel eyes, 8000K headlights & HID fogs, rebuilt alternator & mounting bracket gasket, sunroof seal, CCVs, plugs, sway bar bushings, timing & valve cover gaskets, valve stem seals, guibo joint, mechatronic sealing sleeve, trans fluid, sanded headlights...