There are ways to do this, but they are all VERY complex.
One way is to find the template that drives ALL datasheet views. The good news is, you COULD, if you wished, modify its properties. The bad news is, there is only ONE such template. If you change it for table A, you change it for EVERY TABLE IN YOUR DB!
Another way is to export the table to a real spreadsheet, then write some VBA code to modify alternate columns of the real spreadsheet.
Beyond that, no joy.