How to refinish a claw foot cast iron bathtub?

I have a claw foot cast iron tub in my bathroom and inside it there is a spot where you can tell the water spout once leaked, being that there is some rust developing near the drain. Is there any type of kit that I can use to refinish my tub? As far as I know, I should just be able to take a wire brush or steel whool to the drain area to remove the rust and then just reseal using a porcelin paint and/or protective clear coat. Does anyone have any suggestions? Please help as I really don't want to call in a professional and waste $400. Thanks.