when you have dynamic metadata, you can not use data flow task. because data flow task doesn't support dynamic metadata.
but you can use another solution:
use a foreach loop container to loops through your excel files.
then add an Execute SQL Task inside the foreach loop,
and set a variable value dynamically with the script for import.
you can use OpenRowSet method to select data from your excel file and insert into destination sql server table.
this is a sample command for OpenRowSet:
SELECT * INTO XLImport4 FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0',
'Excel 8.0;Database=C:\test\xltest.xls', [Customers$])
also this is good reference :
http://support.microsoft.com/kb/321686
http://www.rad.pasfu.com