Hi, In that case you need two things,
1) You can have your local task service running with LocalHTWorkItemHandler that will work fine
2) Then you need to have a task service exposed via a transport (Web Services for example) and make sure that the server is also associated with the session that is running the processes, so they can be notified if a task is completed via the Task Service that is exposed via web services.
Notice that you have 2 task services, but they share the database, so they share the state.
Cheers