Hi,
You can set the value in the starttask of process definition.
Use executionContext.setVariable("bpm_assignee","abc");
Use executionContext.setVariable("wf_approver,"xyz");
Below snippet is given:
<start-state name="start">
<task name="XXXX" swimlane="initiator" >
<event type="task-end">
<action class="org.alfresco.repo.workflow.jbpm.AlfrescoJavaScript">
<script>
executionContext.setVariable("wf_approver,"xyz");
executionContext.setVariable("bpm_assignee","abc");
</script>
</action>
</event>
</task>
When you have to use these values you can put as mentioned below in review task.
<assignment class="org.alfresco.repo.workflow.jbpm.AlfrescoAssignment">
<actor>#{wf_approver}</actor>
</assignment>
</event>
Thanks,