Custom Formatting

For reporting our company uses the following formats for numbers and dates. I want to use a custom format to display a recognizeable date

Weeks
10901 = Fiscal Week one of 2009 or Fiscal Month of 2009

I would like to make it just read
10901 = Week 01
and in a different cell
10901 = February 09

Thanks,

Matt

Sorry, don't understand the explaantion of the format breakdown
"Fiscal Week one of 2009 or Fiscal Month of 2009" which is it? What are the constituents of this string?

CC