Org Chart Wizard and Excel Tabs

I want to keep org charts for different customers in individual tabs of a
single spreadsheet called "CustomerOrgCharts.xls). Is there a way I can tell
visio to look at a particular tab when I run the wizard? I don't want to have
to creat a bunch of separate spreadsheet files (i.e. customer1.xls,
customer2.xls, etc.)

P.S. I am using Excel2003 and Visio2000. If this is not possible in
Visio2000 but can be done in a later version, I can probably upgrade to get
this capability.

Thanks in advance!