Your examples don't include a cell with more than one period, but it sounds like you also have things like 2.1.1, 2.1.2. As Duane states, that's not going to turn into a valid number in Access no matter what. BUT - you are implying that your reason for exporting the data to Access is ONLY for sorting options? Can you change the underlying structure to always use 2 (or 3, if necessary, digit "numbers", and then a text sort would work. For example - 02.01.01 and 02.01.02
You could use formulas in Excel to do a batch replacement in the data, and then use the text field in your pivot tables.