Actually, though there is a common principle, that solution was geared for Excel rather than Access.
For Access, to do the same sort of thing manually or in VBA:
- Import your CSV to a staging table that has all the CSV columns plus a month identifier column. This could be date type e.g. "31/12/2009" or text "2009-12" as you prefer.
- Use a parameterised update query where the user enters the month date or string to update the staging table 'Month' column.
- Use an append query to add the imported data, complete with month identifier into your main data table
- Use a delete query to empty the staging table ready for next use.