☛ • Add a reference to that class.

☛ • Make sure your Orchestration is Long Running transactional.

☛ • Add an Atomic scope.

☛ • Create an Orchestration variable of that class inside the scope.

☛ • Create an instance on that object inside the scope.

☛ • Call the method.

☛ • Bonus: Mention the class must be strongly signed and in the GAC.