Hi Victor,
I'm not quite sure yet what you are trying to achieve, but if you are simply setting a default value of a repeating table on your form, in SharePoint 2010, please proceed to the Data Tab, and click on Default Values. If your form has a repeating table in it, you should find something similar to this:

Right click on the repeating group and add another repeating group below. Then select the field/s you want to set the default values to and enter the data. Hope this helps.
Regards,