Need Rolling Prior QTD Only (CPOI) Column Set for FSG

Hi.
We are trying to develop a report with the following column set:

1.  Current Month (Offset = 0, YTD-Actual)
2.  Previous Month (Offset = -1, YTD-Actual)
3.  Prior Quarter (Column Name = &CPOI2, Control Value = 1)
4.  Prior Year Actuals (Column Name = &CPOI2, Control Value = 2)

On the control value on the report, we set the following:

Control Value         Period Number         Relative Year
-------------------------   ---------------------------    -------------------------------
1                            ?                              0
2                            12                            -1

I can easily get prior year actuals, but how do I get the variable Prior Quarter YTD balances?

This should be a rolling QTD balance.  For example, when I run the report for JUN-09, I should return MAR-09.  When I run the report for JUL-09, I should return JUN-09.  When I run the report for OCT-09, I should return SEP-09.   CPOI& doesn't work for this since I want a different quarter, depending on the month that the report is run for.