Both are possible. Search the wiki/forums for additional info
As I said I already tried to look in the wiki and forums to solve the problem. I always do. But I could not find the answer.
Have you tried to create the jBPM database in the RDBMS you're using? That way, it will be easier to acomplish your mission. Chapter 8 explains how, step by step, and jBPM includes scripts for many RDBMS (in case they didn't included it for your DB, you can always create your script, is not difficult, almost trivial with tools like ERwin, and then contribute to the comunity by sharing your effort and experience).
but as I understood in the chapter 8 its only defined how to create the database. My database is already created in oracle database. My problem is when I need to create a new feature that should use the same connection that jBPM does.