How to spread annual forecasts by month across fiscal years by variable start date

We forecast projects annually for new product launches. We also operate according to a corporate fiscal calendar which starts May 1 each year. For any given project, the start of ship for that project can vary. I want to be able to take the five year projections and spread them by month across fiscal years for 60 months according to the start date (start of ship) that is provided for that project.

For example:
Start Date 2/1/13
# months in yr 1: 3
# months in yr 2: 12
# months in yr 3: 12
# months in yr 4: 12
# months in yr 5: 9

Any and all help to accomplish this would be most appreciated!