I've seen a few threads on how to tap into the on-board air tank for tyre inflation (and limited emergency pneumatic tool use), and decided to give it a go myself the other day! Here's the parts you'll need in Pirtek speak:
LPBV - 2 Way mini ball valve (female to female)
M20 X 1/4" Metric to BSP reducing bush (I exchanged this for a 90 degree of same threads after first install due to space restrictions)
No. 73 3/8" to 1/4" reducing nipple
CUPLA nipple BSP - Male
The Ball valve and nitto fitting (last on the list) are steel, the rest are brass, all use thread tape and please get yourself a new O-ring before installing!
It works the charm now! I deflated all 4 tyres to 15psi (highway terrain) and managed to pump 2 up before the tank was getting low in pressure, so it will certainly be one of those things that either tempts me to get a larger compressor or just be more patient in the bush! Would be handy when putting the spare tyre on and realising that it's got no air!! Same if helping Beemer drivers too!
I also put a little glad bag and big rubber band over it to keep it away from the elements! Just need to keep a few of each in the car when going bush!
Hope this helps someone else!