I am not quite sure what I am reading here, it might be that someone has figured out how to take BMW's phone module from a new car and put it into their older BMW to take advantage of the IBUS controller.
It seems to be from the UK, not sure if that means it will translate here.

In openbmw@yahoogroups.com, "Rob" <easyloverand69@h...> wrote:
Just wanted to let everyone know that I have successfully
retrofitted the BMW bluetooth kit part number 84 64 0 302 161 for a
E39/touring to my 99 740i.

It is very simple but there are a few notable changes you need do to
make it work. Firtsly I had a factory fitted phone kit so I did not
need any of the power wiring looms, I only needed the bluetooth
wiring loom. This can all be connected as in the installation
inscructions, the only place where the whole new BT wiring loom
needs connect into the car is at the white 12 pin X400 plug. You
actually get a new top part of this plug as part of the new loom as
the top part of the X400 plug that was in my car was connected to
the old phone loom.
The good news is that the hands free mike has a 3 pin plug in the
boot, so you can just disconnect the plug here from the old loom and
plug in the new plug from the BT loom (no need to rip out all your
headlining to install a new hands free mike!!!)

NOW FOR THE IMPORTANT BIT... The new BT loom installation
instructions says you need to connect 4 wires to the radio unit (2
separate wires for tel mute and tel on and two wires into a plug to
connect into the radio (these are for speaker +/-). The problem is
that the radio in the E38 does not have all these connections. The
two wires for Tel mute (brown/white) and Tel on (green/white) can be
connected into the top of the new X400 plug in to the same pins as
the brown/white and green/white wires already in the plug. (ie you
should have two brown/white and two green/white wires in top of the
new part of the X400 plug.

From the bottom of the X400 plug remove the current black/brown and
black/white wires these are the speaker +/- wires that go to the
front speakers, plug in the wires from the new wiring loom into
these now empty sockets as shown on the installation instructions.
What you should now be left with is 4 wires. The two wires that you
removed from the bottom of the X400 plug and two wires connected
into a small black plug that should go into the new generation
radio.
Here's the trick the bluetooth audio signal NEEDs to be amplified,
the old factory phones motorola/nokia etc does not. You need to cut
off the small black plug and install a small preamp (search on
google for ELK-800, this is perfect for the job) in between these
two wires from the new loom and the two wires that you removed from
the bottom of your X400 plug. After this it all works perfectly.!!!
Because BMW does not supply this pre amp that is needed this is why
they say it cannot be done.

Sorry if this is unclear but it is difficult to explain with out
showing the diagram from the installation instrcutions.

Anyhow I am totally happy as I have an E38 1999 740i with bluetooth
fully fucntional with my steering wheel controls, voice activation
and all my phone book numbers from my phone etc on my NAV display,
just as it should be.!!
..
Im using Siemens S55 and its perfect..! BMW also offer a snap in
connector for this and the Nokia 6310i I beleive this basically
charges the phone and uses the external aerial.
They are no electrical differences between the E38 and E39 in this
case. The part number I mentioned is the complete retrofit kit for
and E39/2 (touring)
Everything is in the kit apart from the little amp you need to
source. (This is why BMW say it doesnt work in older cars as the
required pre-outs are not available on the older radio module)
The amp (from the US) was about $30, the complete BT kit from BMW is
about £600 (pricey I know..!)
Yes the kit comes with a cradle that should fit exactly in your arm
rest (it actually included a new arm rest for the E39) although if
you already have a phone system you wont need the new arm rest. The
snap in connector for your phone is not included as it is not
necassary to make the kit work.
Here are some more instructions.Firstly go download this pdf.
http://www.tru64.org/~jmh/x5/phone/bluetooth.pdf
This is for the X5 but for out purposes it is fine. Forget about
harness P you dont need it.
What you need is the main loom A and the loom B.
Loom B is easy it just connects the little plastic Bluetooth antenna
(WDCT aerial) to the BT ULF.
Loom A is the main wiring loom. So here goes....
Follow the instructions as per the pdf.
A11 to the ULF module.
A12 to the phone antenna (probably will need to change the connector
on this to fit with the one you have in your car, that is assuming
you have a phone antenna already) A8 to the antenna power booster
(optional, don't know if you have this, I do) A10 (2 wires, DO NOT
connect these to the radio as it says as our radios are not the same
as the new gen) Connect these two wires white/green, white/brown in
to the top of A6 into the pins that already have white/green,
white/brown so now you have 2 wires of the same colour in these pins.
Connect A6 (this is the top of X400) into the bottom of your X400
plug (you will have removed the top of this with your old phone
loom).
Take out pins with black/brown and black/white from the bottom of
the X400 plug and replace with the same from A7.
Now you have 4 wires not connected these are A9 (cut the small black
connector off) and the wires you have just removed from the bottom
of your X400. These are the ones that need to be connected into the
small preamp you need to source.
Then plug A5 into your existing mike plug (again you will have
unplugged this when you removed your old loom) and then obviously
connect A1 and A2 to the cradle, and you are all set!!!
My advice would be connect all this up in the boot and test it works
first, although you need to press the pairing button on the cradle
(keep it pressed) and then turn on the ignition then release the
button to initiate paring so just walk round the outside of the car
with the loom connected to the cradle (its long enough just)and the
carry out the pairing as in the instructions.
That is it. It took me about 20 mins to disconnect my old phone loom
and about 20 mins to connect up the BT kit and test it all works
fine. The time consuming part is to actually run the loom for the
cradle under all the seats etc, and to completely remove the old
loom...
Hope this helps.