Reviving this thread because at the time (Aug of 2016) the 2017 release was still in development.
The following November SketchUp 2017 was released and now has a user appdata "Components" directory folder. So since v2017 user component collections are more accessible.
comp_path = File.join(
File.dirname(Sketchup.find_support_file("Plugins")), "Components"
)
# >> C:/Users/Dan/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Components
File.exist?(comp_path)
# >> true
When your extension loads, you can check for the existence of your plugin’s named sub-folder in the comp_path directory, and if false then copy your component folders over to a plugin specific comp_path subfolder.
plugin_component_lib = File.join(comp_path,my_plugin_dirname)
unless Kernel.test( ?d, plugin_component_lib )
Dir::mkdir( plugin_component_lib )
copy_component_folders( plugin_component_lib )
end
You may wish to load FileUtils from the Ruby library to help with the copying tasks …
http://ruby-doc.org/stdlib-2.2.4/libdoc/fileutils/rdoc/index.html
After doing this, the Components browser may need to be refreshed either via UI.refresh_inspectors() or having the user switch folders and back to the root again. (Worse case would be SketchUp needs restarting, but that is usually the best action after installing major extensions anyway.)