I was very lucky to have someone email me the LOADING.KWI file. I burnt it to a CD-RW and it worked.
I know that most folks won't care about the original Denso Nav Radio, but if you have an original Seville/DeVIlle and want to keep it that way the Nav Radio's weakness is that if ever the car's battery is disconnected for long enough, there's the risk that the radio's back-up battery will discharge (these batteries are now about 15 year-old, so even more prone to failure now).
If the Nav radio's battery fails, the radio loses its software and then you don't have a working radio/CD/Nav anymore. It's bricked.
It's funny how up to maybe 3-4 years ago there were so many threads about this. People were begging for copies of the software to get their radios to work again. I posted this info on the 'other' Cadillac form, offering to make the software file a sticky, and nobody was interested! Everyone must have aftermarket radios now instead of the Nav radio.