So I wrote recently about wanting a USB port for iPod /phone charging inside the armrest/cubby box on my E63, here’s how I achieved that. I thought about where to pick up a power source, I was focussed on the cigarette lighter initially but accessing the rear of that means a fair bit of fiddling and removing the gearstick trims, eventually though i concluded that (where fitted) there would be a positive and negative supply to the phone charging cradle inside the armrest and tapping into this would be nice and easy, in theory.
So, to start, i prised out the AUX socket and disconnect the plug. This is a simple push pull plug but was REALLY tight. Next pull up on the cubby box tray floor via the now empty AUX port hole which has a snap fitting each side at the rear and a wedge fit at the front, its on slide/guides with the vertical rear flap too, it will then lift out. Locate the multi-plug fixed in the lower regions which supplies power etc to the phones cradle situated above. Separate this for easier access. Power is the red wire with tracers and earth is brown as normal. Tap into these two wires which are permanently live according to my meter.
I sourced two types of USB sockets and really wanted a double but with the power reduction gizmos inside them a double was going to be tricky to locate being just too long to fit where I wanted it, bearing in mind a cable will be coming from it and you still have to get a device inside the cubby box when closed, so I opted for a shorter single version, this one
http://uk.rs-online.com/web/p/automotiv ... 63126 I located this as shown adding a split connection should I ever want to get it all apart again.
Was it worth it? Well I can now at least use an iPod without worrying about battery life and alternately I can charge my phone as well as play music from it too. It can all be kept out of sight and not sliding off the passenger seat under occasional harsh braking.
Total cost for this was about £25 (the USB socket above plus some connectors) and imo it was well worth the effort, I wish it was a double port but to be fair the internal space is so restricted I don’t think even my phone, a slim A3 Samsung and a mini iPod would easily fit in there simultaneously anyway, not with cables tucked inside a small space. This, for me anyway, is so much better than cigarette lighter adaptors and cables trailing all over the place. I know the iPod playback doesn’t interface with the monitor display (nor would music played via the phone) but such systems are circa £500 fitted and this gives me my prime requirement of a power/charging source and its hidden away and all for peanut money.
This is all specific to a pre-facelift E63/64 of course but the principals may well apply on other older BMW’s too.
My objective was achieved
The starting point, floor of cubby box removed.
What lurks beneath?

Identify the 12v supply, red/blue with yellow, and earth, brown.
Connect the crimp-locks. I dislike these but space is so limited it seemed the best option. I added a split connection to the socket for future easy access if required.
A 28mm hole drilled and USB port fitted. The space underneath is very limited so i opted to fit just off centre where there was visibly more clearance underneath.
Job done and looks like it was meant to be there.

2009 35d, Space Grey with Chateau leather, still below 40k miles.