I've seen a post buried in the forums on how to add an auxiliary input into a head uni with B&M. This is how I did it...
Basically, you have to spline a wire to the current aux input (from the Blue&Me) and then play a silent audio track through the media player and you can listen to anything you want :)

What you will need:

1) Disconnect the NEGATIVE terminal of your battery or the fuse for the radio.

2) Remove the head unit using the radio keys. Insert them into the holes, add a little pressure outwards, and pull the head unit out. Unplug all the plugs in the rear of the head unit.
remove.jpg


3) Locate the auxiliary input currently going B&M into the head uni. The yellow socket in the photo.
back.jpg


4) Strip back the velcro stuff using a Stanley knife. For this I put the stanley knife in-between the wires and ran it in the same direction of the wires to cut the insulation down the middle.


5) Prepare your phono lead. I'm using a phono lead to make it easier to connect and disconnect wires (I'll be fitting a jack into my centre console which will be shown in another guide).

a) Cut off the 3.5mm audio jack.
cut off.jpg

b) Strip the insulation and twist together the ground wires (the copper wire on the outside of the inner insulation of each wire).

c) Strip the insulation of the other two wires.

prepare.jpg


6) Strip the insulation of the current aux input wires from B&M - Strip about 15mm off each wire. I'm sorry that I didn't get a photo of this one. But you want to strip the insulation about an inch away from the socket. So that another wire can be spliced onto each of the three wires. You'll want each wire to look like the photo below.
FCQWR1FFRXUSAGH.LARGE.jpg


7) Splice the phono wire to the aux input. Solder the following wires to each other...
Grey to White
Black to Ground
Green to Right.

splicing.jpg

Tape over all the connections with insulation tape to stop the wires touching eachother - Don't laugh at my dreadful soldering :p

finished plug.jpg

8) Thread the phono lead down the back of the dashboard to come out wherever you please.

plugs.jpg

9) Connect the head unit back up, put it back in, and you're done with the practical part.

Just connect a cable to your phono connectors and you can listen to whatever you want. HOWEVER...

To get the sound blaring out of your speakers you'll have to have the radio in media player mode (playing from a USB stick). This means that two songs will be playing at the same time.. So what you need to do now is create a silent audio track to play in the background whilst you listen to songs through your new aux input.
(I would have attached mine but its 109MB).

What I did was....
Download Audacity.
At the top click Tack>Add New>Audio Track.
Then at the top click Generate>Silence...
Set the time to whatever you want (mine is two hours long for some reason).
Save to MP3, and you're done.

You can now play this silent track in the background and listen to whatever you want through your new aux input :)