How to add configurable attributes to flat product table

I was wondering how to add configurable attributes to the flat 开发者_开发技巧product table. I have attributes of size and color with "Use To Create Configurable Product" = Yes, and when I change "Used in Product Listing" to Yes and reindex, I get size, size_value and color, color_value fields added to my flat product table, but there is no data in it for any products, however my configurable products do have values for size and color.

Changing an attribute to "Used in Product Listing" = Yes works well for general attributes , but doesn't seem to work for configurable attributes. Can this be done?

Thank you!