Achiving Multi Level Approvals in bo event based workflow

Hi Everyone,

I have one requirement related bo event based workflow. I am triggering the customizing workflow when sales order number is created va01 through bo event ( Created ).

--->Here my problem is how to achieve multi level approvals? Is there any blog related to bo event based multi level approvals.

--> I tried like this to achieve multi level approvals for the above requirement.

1. intillay i configure bo event in basic data.

2. I created one until loop , then i add activity step, In that am calling se24 class for getting agents in in background mode. But the work item will be Dailog step. ITs not taking background mode. plz guide me if any did wrong.

3. can you please guide me how to achieve multi level approval bo event based worklflow. This is customizing worklfow.