Normal Calendar to Factory Calendar

Hi

Normally when we use 0calday,0calyear etc in out cubes the year starts on the 1st of Jan and ends on the 31st Dec and similarly a month starts on the 1st.

But for the client here the month starts on the 21st and ends on the 20th of the next month. Now I have changed the spro settings to start the day on 21st. But how do I enforce that 0calmonth in my cube must follow the factory calendar setting and not the normal calendar.

Your help will be greatly helpful.

Thanks,