Making the CVV field manadatory….

I need to make the CVV field on my site marked mandatory with an astrik*, and don’t know how to do it. It’s not a field in the settings checkout section, and when I try to make it one, it just creates a whole new field, but it won’t let me edit one that’s already there.

I have wp-ecommerce with gold cart and authorize.net.
I used to have it marked as mandatory, but it disappeared with the upgrade. Now, customers don’t know they need to enter it, so they aren’t, and their transactions aren’t going through, and they don’t know why…

Help is greatly appreciated…