Hi khany,
I'm just about to do the same thing to my MMi 2G High, i downloaded all 3 disks from a link in the description here:
Disk 1 & 2 deal with the firmware updates and Bluetooth module, the third is a DVD for the sat nav.
BUT BEFORE YOU DO THIS........
make sure you watch the video to disconnect the fibre optic feed to the stereo amplifier (especially if its Bose etc).
You also may have to complete the installation more than once to step up revisions in the f/w.
First support post for me on here, so hope this helps and I've done it correctly.
Let me know how you get on
(edit) : found the same info deeper in this forum: