So i wrote to logitech support and this is their reply. Hope that helps a bit.
"Our UE4 plugin is a code only plugin, so it does not have any blueprints available. Blueprints are definitely something we’ve talked about for a later version, but there is no support yet.
As for the documentation, its buried deep within the unreal engine directory under the LogitechG plugin folder from the marketplace (“Epic Games/4.xx/Engine/Plugins/Marketplace/LogitechG/Doc”). The “UsageInstructions” contains a simple getting started guide that shows how to call the plugin from c++ code. For more a more in-depth guide on each of the SDKs (Steering Wheel SDK for example), they can be downloaded from our developer page.
If you have not used the Steering Wheel SDK before, I recommend looking at the c++ sample project included in the bundle from our developer page. It will give you an idea of what a complete implementation looks like."