ExcelBanter - Pivot Table Dates

I have a pivot table that takes data from 6 columns:
A - Current Yr Week (1, 2, 3 ...)
B - Current Detail Date (1/1/09, 1/2/09, 1/3/09 ...)
C - Last Year Week (1, 2, 3 ...)
D - Last Year Detail Date (1/1/08, 1/2/08, 1/3/08 ...)
E - Current Yr Unit Cost
F - Last Year Unit Cost

My goal is to have this daily information compiled into weeks (totaling at
each Saturday). Since columns B and D have daily values, to get true week
end values, I would need to have 3 columns in my pivot tables:
A - Week # - 1, 2, 3 ...
B - 2008 week (listing down the column like this, for each Saturday: 1/5/08,
1/12/09, etc.)
C - 2009 week (1/3/09, 1/10/09, etc)

I'm sure something like this is possible, but I'm not sure how to do it?
Any suggestions would be greatly appreciated!

Thank you for your time and help!