So I was recently messing around with a 2005 Lexus GX470 with Nav also made by Navteq.
On the Lexus, one can do a procedure to enable changing destination while driving; much like the Land Rover. However, after doing some research they also have the same issues with the "loading.kwi" file. The latest version of the Nav DVD cannot be hacked to enable destination on the go. When the lastest DVD is installed,"loading.kwi" installs a file that blocks the destination on the go. Some claim to have made "hybrid" discs, but I've tried many many times and didn't get it to work.
Here's the interesting part, if one updates their Nav system to a newer version of the software and accidentally blocks the ability to change the destination on the go, they can fix it. All you have to do on the Lexus is, put the old DVD in the player, and unplug the battery terminal for about 10 min. Once the memory seems to be erased and the terminals are hooked back up, it then installs the software again. Based upon whatever disc is in there, you can once again use the destination on the go feature, but with old maps of course.
My question is, who here has a 2005 or early 2006 that originally had the 2004/2005 DVD. Then, if you updated the Nav system to a official LR DVD and blocked 1791, try the procedure above. I think I remember someone saying something about this perhaps, but it's worth a try. If it works, it may work on newer LR models too.
Here's the Procedure if you don't have 1791:
Eject the more recent DVD you have. Put the 04/05 DVD back in. Unplug the battery terminals for 20 min maybe 30. Hook the terminals back up, see what happens. I myself would try it, but I am still running the 2008 DVD. I like my 1791 ability too much.
If it works, this could be interesting...