I agree that eventually we should be able to find an answer that sounds as reduced as an answer to "How does blood flow work?" does. But from where we currently stand, they seem to be really, incredibly fundamentally different questions...

Ok, that makes sense. I understand now that this is what you believe, but I still don't see why. You say:

But from what we can currently tell, there doesn't seem to be even an in-principle plausible mechanism for adding qualia to a computer's way of processing things. A computer receives input, does some well-defined manipulations, and offers output. Where do qualia come into play?

This, to me, sounds like a circular argument at worst, and a circular analogy (if there is such a thing) at best. You are trying to illustrate your belief that qualia are categorically different from visual perception (just f.ex.), by introducing a computer which possesses visual perception but not qualia, because, due to the qualia being so different from visual perception, there is no way to grant qualia to the computer even in principle. So, "qualia are hard because qualia are hard", which is a tautology. Your next paragraph makes a lot more sense to me:

I guess the categorical difference is that when asking about blood flow, there's someone who experiences the question and the data and the subsequent answer; but when asking about consciousness, it's the very process of being able to understand the question in the first place that we're asking about.

I think that, if you go this route, you arrive at a kind of solipsism. You know for a fact that you personally have a consciousness, but you don't know this about anyone else, myself included. You can only infer that other beings are conscious based on their behavior. Ok, to be fair, the fact that they are biologically human and therefore possess the same kind of a brain that you do can count as supporting evidence; but I don't know if you want to go that route (Searle does, AFAIK). Anyway, let's assume that your main criterion for judging whether anyone else besides yourself is conscious is their behavior (if that's not the case, I can offer some arguments for why it should be), and that you reject the solipsistic proposition that you are the only conscious being around (ditto). In this case, a perfect sleepwalker or a qualia-less computer that perfectly simulates having qualia, etc., is actually less parsimonious than the alternative, and therefore the concept of qualia buys you nothing (assuming that dualism is false, as always). And then, the "hard question" becomes one of those "mysterious questions" to which you could give a "mysterious answer", as per the Sequences.

You might find it helpful to read the Wikipedia page on the hard problem.

I'd actually read that page earlier, and it (along with associated links) seemed to imply that either dualism offers the best answer to the "hard question", or the "hard question" is meaningless as per Dennet -- which is why I took the time to slam dualism in my previous posts.

Again, I think that was Yvain.

Darn, again, I'm sorry. But nevertheless, I think it's a good thought experiment.