It is not possible to add a column in the first (or leftmost) position. If you add a column to a table, it will always be in the far right position.
The only way around this (that I can think of) would be to create a second table, and add the column you want. That column would then be in the leftmost position. You would then have to basically copy all of the columns from the first table to the second table, and then copy the value of each cell from table1 to table2.
You could then dispose of the first table.
Make sense?
Gary