I found this link with info about the part numbers for the NAV:

BMW pre-installed system - TFT ? - MP3Car.com

According to that it is a Sharp LQ065T9BR52 or LQ065T9BR51. If anyone has a source, I would be game to try it. I assume it is just a ribbon connector to fit (fine pitch, but nothing crazy).

Here is a source for the screens:

Sell BMW E46 LCD LQ065T9BR54U (KECO Technology CO., LTD)