Help!

I have a large box of Complete Buttermilk Pancake Mix that I'd like to use to make cornbread. We eat a LOT of cornbread, and I have liked several cornbread mixes, but this big box of Pancake Mix is going to waste.

How much ground cornmeal do I add? There is a recipe on the box for whole-wheat pancakes that adds whole-wheat flor, but it's for the whole box and I don't want to make THAT much for the first experiment!

???

~Susan