Project Manager Approval for Time Sheet

Business requirement:

Ours is a professional services organisation mainly into IT project executions. We are implementing the SAP time sheet application (with SAP portal) as part of the O2C process. Employees are required to fill time sheet. Approval of the recorded times through the time sheet is mandatory. There could be two scenarios, one line manager approval, two approval by project manager. We are OK with the line manager approval however there is not standard functionality provided by SAP. This is a critical business requirement & we need to implement.

Solution approach:

We are planning to use approval without workflow.  To cater to the project manager approval SAP we are implementing the SAP suggested BADI refine settings for approval, method Change Number of Records to be Approved & class IF_EX_HRCATS_APPR_CUST~EDIT_SELECTION.  This would allow use to implement the requirement. However  the class is standard class which contains commented example code which we need to activate but system is asking for access key which we want to avoid. Kindly suggest technical way forward to implement this functionality.