Sosa distinguishes between particularism and methodism. Methodism starts by outlining what the correct epistemological methods are, and then checking to see how much knowledge we have given those methods. Most people don't really do that, I don't think. Much more common is particularism in epistemology. This is a methodological starting point; you start with knowledge, and then you attempt to justify and understand what norms and principles give us that knowledge. It's not just an attempt to describe our knowledge, but that description is in fact normative in this case. If it turns out from our study of knowledge that people require observation in order to know stuff, then observation is normative, in the sense that you only ought to believe something if it's been observed. That's the methodology for a lot of epistemology.
You might ask, then, why not do the same thing for ethics? Say that we're assuming that there is ethical knowledge, and that we need to understand how that's possible. Then how we gain that ethical knowledge is normative. Given that we do the same thing for epistemology, how can we distinguish the two?
The obvious difference is that whether there is ethical knowledge is debated. But I suppose if one was quite sure, on a first-person level, that there was ethical knowledge, there's nothing to stop him for proceeding as we do in epistemology. But it certainly won't convince anybody. But it's not aiming to. Just as epistemology often says that it has no need to answer the absolute skeptic, a moral epistemologist could say the same thing. Of course, it won't convince the skeptic, but maybe one doesn't want to. This only works if you are REALLY sure that there is ethical knowledge, but given that someone is this certain then it's hard to think of a way to criticize their methods given that there's an exact parallel methodology in scientific/general epistemology.