Use a stored procedure as the source of the data to export, declare a table variable as having an Identity column as the first column, then define the rest of the columns from your original table.
Declare @TextSource table(
NewCounter int Identity (1,1),
OrigTableCol_1,
OrigTableCol_2,
...
)
//fill the columns with the data from the original table, NewCounter gets incremented automatically
Insert into @TextSource (OrigTableCol_1, OrigTableCol_2, ...)
Select OrigTableCol_1, OrigTableCol_2, ...
From OriginalTable
Where (if necessary) ...
//return the contents of the table variable
Select * from @TextSource
This will give you your original table plus an identity column. You can start the counter at any value you want and increment it by any value you want as well, just change the seed and increment values when you declare it.
NewCounter int Identity(seed, increment)
Glen