I just did this and it seemed to work:
1. Create a 3-column repeating table.
2. In the second column, put this formula:
substring-after(../my:field1, ",")
3. In the third column, put this formula:
substring-before(../my:field1, ",")
4. Save the form, and then open in Fill-out mode.
5. Click inside the first column of the first row and insert enough blank rows to receive all of the data you are about to paste in. This can be done by pressing and holding ctrl+enter.
6. Open your word document with the table. Select the the entire column by clicking at the top with the black downward arrow thing.
7. Switch back to InfoPath, click inside the first column of the first row to set the insertion point.
8. Paste. (Depending on how many values you're using, this might take a while)
9. Click outside the repeating table to trigger the formulas on the second and third columns. (This will probably take even longer)
Shaazam!
Hope this helps!
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge