Yes, good luck Sparcomx. I have also ordered the parts, although for my June 07 X5 rather than my e90 M3 (that already has USB).
They are much the same bits as the e90 but the USB hub is mounted on a bracket instead of in a box. Also there is no additional cable listed in the parts catalog.
The prices I paid for the main items were (plus taxes, etc):
84 10 9 123 739 :USB hub $72.27
84 10 9 134 266 :Bracket $3.21
61 31 9 129 652 :USB/AUX-IN socket $39.44
So no big outlay. I will need another Y cable also if it works.
I haven't yet worked out where they go but I suspect that Sparcomx is right that it is somewhere behind of the radio.
If it turns out to be easy-ish to install and needs no coding then it could be a better deal than a factory-fit 6FL.