Hi Chris....
Even i am facing the same problem as lakshmi. I tried adding the new users to the files you mentioned in the post and running the evaluation process with the new users, but its throwing exceptions.
I tried adding new user "tony" to these file-
1.jbpm-installer\task-service\resources\org\jbpm
2. jbpm-installer\jboss-5.1.0.GA\server\default\conf users.properties and roles.properties
Please help me
Thanks.....