In terms of loading the software: send the command from NavCoder, wait until the nav shows no activity - this is the nav waiting for you to load the CD - insert the CD, and wait for it to be ejected again. You'll hear the nav accessing the disc and loading the software. When the disc is ejected, remove it and click the nav rotary button on the display. The nav will reboot.

Note that noone has yet succeeded in doing this recode, even though NavCoder emulates the GT1 procedure. I am not sure why there has been no success.....???? Let me know how you get on.