Library is available on Nuget -
Install-Package w8ga. Very simple installation.
Browse
https://nuget.org/packages/w8gaGoogle Analytics for WinRT/Metro apps for Windows 8
2.4 version supports:
- Pageviews tracking using AnalyticsHelper.TrackPageView method
- Event tracking with AnalyticsHelper.TrackPageView method
- Custom variables
- Device manufacturer tracking
- Device model tracking (see custom variables #1 (is it a custom pc or a manufactured model), #2 (manufacturer), #3 (model), #4 (manufacturer + model), also see Events->Device Models->)
https://developers.google.com/analytics/devguides/collection/gajs/gaTrackingCustomVariables
What is not supported:
How to use Google Analytics in your Windows 8 Metro app (link to tutorial)This component requires your app to have "Internet (client)" capability enabled:

Sample app is included, see "Source code" tab
This is just a hosting of a source code,
If you need to improve/fix/modify code, please use patch feature or contact somebody from Team