Basics
Both Android developer and Chrome OS developer sites have sections to support stylus for Android app. Those sections even mentioned Wacom. All the basics to build a stylus-aware Android app can be found at those official sites.
The link below guides you through the Android app development process, step by step:
Start building apps for Chrome OS | Android Developers.
There is a list of action items to adapt Android apps to Chrome OS . Please search "stylus" in the Optimization and Test sections for tablet related input actions.
See Also
Overview – Information on the Android API
Basics – Details on tablet specific Android API
Reference – Links to the complete Android API packages and classes
FAQs – Useful Android programming tips
Sample Code – Full Android API demo sample