Yeah, you have to put the files in ...\Marmoset Toolbag\base\sky\ So I put this pack in \Program Files (x86)\MarmosetToolbag\base\sky\custom and it works. Won't work from anywhere else: http://www.marmoset.co/ToolbagUserManual.pdf
cman2k: Thanks, hope you find some use for them :) Here is a few light environments I have created today. https://dl.dropboxusercontent.com/u/1506599/light_pack01.rar Put them under "\Program Files(x86)\MarmosetToolbag\base\sky\custom"