Its right out of the Bently Manual. (BAVAuto has'em on sale right now)
In the trunk, after you remove the spare tire, on the passenger side just behind the back seat, is an air distribution manifold with two different colored (mine are red & blue) plastic air hoses. Fastened with a compression fitting. Loosen those compression fittings until you hear air hissing out. Give it 10 minutes or so. Then tighten back up - snug, not too tight.
There ya GO!