Fiscal Date Dimension

Hi,

I have a cube with regular date dimension. I want to be able to analyze the data so that each month will actually start from the 22 of the month before till the 21 of that month.

Ex: May will include date range of April 22- May 21.

Do I achive this using the option of Fiscal calendar? (Or how?)

Can I add it to my current dimension or does it need to be a seperate dimension?

Thanks

Namnami