one icon does not a package make
to change an individual icon with icon packager,
open it IPkgr, then click 'icons & cursors'
in the 2nd row pick the category with the icon you want to change
click change this icon
browse to your icon
if you click 'help' icon at the top right corner of IPkgr you'll get this:
https://www.stardock.com/products/iconpackager/help/toc.htm