monthly report with quarter fiscal setting

I have an issue with monthly custom report (fetchXML based) with CRM 2011 online.

Our company fiscal setting is quarter base not month base.

But I have to use month parameter for custom report in BIDS.

Year and Month can be filtered by in-fiscal-year and in-fiscal-period if you use fiscal setting with month.

If you use fiscal setting with quarter, how can you implement this report.

My report is that user select year and month to show all cases in that month.

Thanks for your help in advance.