In the meantime, you might be able to modify the code and examples to meet your needs:
ImportGoogleAnalytics.importDailyMetrics shows how to import a single metric over time. It calls GoogleAnalytics.insertDailyMetrics, which is where the data is saved into the toolkit's custom objects. You would need to modify GoogleAnalytics.insertDailyMetrics to save them into your own custom objects instead.
Matthew