Oooops... I missed this...
Mea Culpa folks - thinking it was a "template", I used the "basic" readme and only changed the intro and storyline. I didn't realise we had to edit all the way down as well. I see we need a fix...
In the meantime, it is basically the same procedure for every addon scenery file:
1. unzip to a new location
2. move/copy the [name of scenery] folder to "addon scenery"
3. activate scenery in FSX library
4. if the authors have added any effects and sound files - it is best to open any "effects" or "sound" folders in the unzip and move the files (as opposed to the folder) individually or as a group.
Fortunately for me, the "Through Glacier" addon is only a single folder that needs moving.
Sorry all.