Among my Cold Steel knives is one of those K7 kitchen knives, fully serrated. I accidentally let it corrode and the teeth got the worst of it. After removing the rust with a green Scotchbrite pad, I realized that the teeth were going to be practically impossible to sharpen, more so because some of them were corroded away.
I got out my bench stones and simply sharpened the blade ignoring the serrations. I just sharpened it as if the blade was a plain edge with no teeth. It looked ugly when I was done (especially from the missing bits that were corroded away), but was as sharp as ever.
Instead of the voids of the teeth being sharpened (like it was when it was new), the "high" parts were sharp. Cutting performance turned out as good as when the knife was new.
If you decide to buy a Cold Steel serrated blade, my advice is don't worry about sharpening the teeth. As long as you care more about cutting performance more than you care about looks, just sharpen it as you would a non-serrated blade and it will turn out just fine.