Is there a way to have a system generated event continue a business processes?

Situation
=======
I have a Seam page flow that create a business process as the last step in the page flow. The business process immediately begins processing the request but as part of the process submits a request to third party vendor that may take several days to complete. Once the vendor completes the task our system will be notified.

I've tried modeling this situation as a wait state but I cannot find any documentation on how to continue the business process. There are references to the @StartTask and @EndTask for user generated continuations that use a request parameter TaskID. Is there something similar for system events that an EJB could initiate (I'm hoping without an http request and creating a system user)?

I've attempted starting the process using the technique described in the JBpm documentation.

JbpmContext context = JbpmConfiguration.getInstance().createJbpmContext();
try {
GraphSession session = context.getGraphSession();
ProcessDefinition processDefinition = session.findLatestProcessDefinition("myProcess");
ProcessInstance processInstance = new ProcessInstance(processDefinition);
ContextInstance contextInstance = processInstance.getContextInstance();
contextInstance.createVariable("param1", paramInstance.getId());
Token token = processInstance.getRootToken();
token.signal();
context.save(processInstance);
} finally {
context.close();
}

This results in the exception
java.lang.IllegalStateException: No application context active
at org.jboss.seam.Component.forName(Component.java:1577)
at org.jboss.seam.Component.getInstance(Component.java:1627)
at org.jboss.seam.Component.getInstance(Component.java:1610)

I believe this is a result of the seam context not properly being initialized.

Configuration
===========
I'm using seam version 1.2.1 with JBoss 4.0.5 with EJB3.0

Any assistance would greatly be appreciated.