I published all of the source code for the my EA tools and add-ins on https://github.com/GeertBellekens

• Enterprise Architect Toolpack
  This repository will contain all of the actual tools and add-ins for Enterprise Architect
  Currently it contains the EA Navigator Add-in, a tool to navigate between operations and sequence diagrams. 
• Enterprise Architect Add-in Framework
  This repository stores all framework stuff to create add-ins and tools upon Enterprise Architect.
  It currently contains an EA wrapper library based on the UML Tooling Framework, the EA Add-In Tester , the complete C# add-in template and the example add-in MyAddin used in the tutorial Create your first C# addin in 10 minutes 
  
• UML Tooling framework
  This repository contains all tool-independent parts of the framework. It is basically a C# translation of the UML Metamodel. 

See my Blog for more info.