You need some software; these are just an example others work just as well;
UltraIso
Imgburn
You need navtweak.
I use UltraIso, it will let you extract the navboot file from the v31.mds file and save back (the new image) to a v31.iso file (ready for cd burning)
Install UltraIso,
Then run UtraIso
File, Open "v31.mds"
Navigate to "V-2/RR/0101/BMWC01S/app_sw" in the now open image.
Drag and drop the navboot out of the image onto desktop (or sub-dir)
Install navtweak (including the GDK librarys),
Open navtweak
File, Open "navboot"
Select the 2nd tab (images)
1: For sky select romicons #8 and right click replace, (with your choice)
2: For splash seletct rombitmaps #14 and right click replace, (with your choice)
3: For 3d icons rombitmaps select rombitmaps (you get the idea)
Then save the navboot (keep a copy of the original safe).
Then drag and drop into the open UltraIso session (back where you found it, "V-2/RR/0101/BMWC01S/app_sw").
The nav unit doesn't allow it to "update" with the same software as already installed. So you have to fake the SoftwareVersion.
do the following: also extract the 2 .tbl files from the directoy:
<drive>:\V_2\RR\0101\BMWC01S
Open it in an HEX editor (like Freeware,
PSPad)
In the first line you find: 30 39 31 30 This means: 1000 So: Software-Version 10.00
Just edit the last 30 to 31 and you nav unit will think it's a new Software Version and you can update your v31/v32 without prior downgrade to V29
The next time you update, you can edit it back to 1000 then 1001 again...
Save the UltraIso image as v31.iso, then burn a cd ad 1x speed.
That's it.