Which year? There is a code for earlier models floating around here. A quick search should yeild the instructions. Even some range rover models use the same PIN codes to enable dvd watching while in drive. Try searching for 1791 or 1971 - i think that is the code.
As for 2006 - I havn't found anything yet, and I have been looking.
The C6 forums came up with 3 codes, 660, 295660, and 9448 from the loading.kwi file on the dvd, but none of those codes do anything in my 2006 and I don't even have a loading.kwi file on my DVD. Those codes seem to get in to the diag screens on C6s.
There are quite a few discussions going on trying to figure this out on other boards, the C6 crowd is much larger and much more aggressive on trying to find a way to do this.
My idea has been to take a look at an update Disc, but I don't think XLR owners have ever had one. The update DVD would give hints on how the firmware is upgraded on the nav unit, that would be a HUGE help. I think I read that SRX owners actaully got a DVD mailed to them and once updated they got added features like MP3 playback, etc, etc. But their navi system is totally different...
Has anyone ever received an update DVD for their XLR?