No one (I think) came forward with citations against Hume's stance on miracles in response to my post, so I did a bit of listening to available options on iTunes about this issue to see if it would do the job:
First, episode 15 of this "Christian Apologetics" course by the late Ronald H. Nash (pictured) of the Reformed Theological Seminary.
His account of Hume starts 22 minutes in, and he gets the problem right: Hume is not saying that miracles are metaphysically impossible, but only that epistemically, we have no justification for believing them. Nash gives Hume's account of causality, which explains why he can't be arguing against their metaphysical impossibility: for Hume, causality is a matter of experienced patterns, not metaphysical possibility. We only read patterns into experienced regularities; it's always possible that something totally unexpected could happen.
Beyond this, however, Nash is totally unconvincing. His response (at 41 min in) to Hume is that statistically improbable things happen on occasion. He gives an example of a tornado that, despite the odds, hit the same place twice.
This is a totally inadequate response to Hume's claim. Hume would have no problem with probabilistic laws, and statistically improbable things are LIKELY to happen occasionally: if you have a bell curve of probability, the outliers are on the curve too. The tornado hitting in the same place twice would on no reasonable account be deemed a miracle, and is nothing like, say, the parting of the red sea, or a burning bush, or water into wine, or guy coming back from the dead, or the sun halting in the sky, or any of that.
Nash then gives some responses from early 20th century English philosopher C.D. Broad: First, if highly implausible sounding events were always discounted, then there would be no scientific advance. This doesn't work for Hume, again, because it's not a comparable case. If a scientist sees something unexpected, it's not accepted as part of a new, adjusted body of knowledge until it's well verified and explored. If it's really that crazy, it's most likely a piece of gunk on the telescope lens or interference from somebody's cell phone or you've got a tumor or whatever. To get it accepted, you need multiple people to witness the event, and verify it repeatedly in as many ways as possible. Hume would have no problem with that, and an alleged new miracle could potentially be discovered to be genuine if it were to pass such a test. But it's no accident that this never happens--no matter how many times millionaires offer cash for proof of ESP and the like--and the alleged historical miracles of the Bible have nothing like that kind of support.
The second argument Nash gives from Broad is that miracles would could potentially leave verifiable evidence, and in the case of Jesus's resurrection, the evidence of the rise of the Christian church can have no other reasonable explanation but that this resurrection must have really occurred. Does this even require a response?
My second find here was much more helpful: Episodes 8 and 9 from the Philosophy for Theologians podcast, which featured I think a very PEL-like group of guys going through a paper presented by student Daniel Schrock. Since Schrock's paper is guiding the discussion, it proceeds methodically: the first of the two episodes (really one long discussion) is all about just presenting Hume's views, and the participants seem to get all the subtleties I've been trying to relate above. They recognize the force of the argument: if you apply rules of evidence that even the most ardent of religious believers invariably applies to his or her ordinary life, then you're going to be extremely skeptical of miracles, and given that you already (presumably) are skeptical about the miracles of faiths besides your own, what reason could you have for exempting those of your own particular sect? (This last point was attributed recently to Christopher Hitchens in what I think is this debate, referred to often in the podcast.)
The critique of Hume has two parts: First, Schrock argues that Hume's epistemology has serious problems in itself: namely, the analytic-synthetic distinction as critiqued by Quine, and second, that Hume's problem of induction undermines his critique of miracles.
I'll have to review my Quine; I honestly didn't see the relevance of the analytic/synthetic distinction to the point at hand. Re. my explanation above, I don't get the second argument either: Hume undercuts our usual conception of scientific laws as iron-clad metaphysical straightjackets. These are instead functions of our expectations. Miracles radically violate our expectations, and if they are not verified, i.e. go through the process to be brought into the system so that they become part of our expectations, then we have to reject them. To me, this seems a coherent account.
Now, I don't buy into this aspect of Hume's epistemology as it happens, and neither does Mackie, which is why his book is useful in evaluating Hume's claims extricated from his particular account of causality. What's important is that both Hume and Mackie have some account of scientific law, such that they can define a miracle and say why it has to meet scientific principles of verification (whatever these may be) to be accepted. If you want to argue against this, then you have to give a coherent account of scientific verification that nonetheless allows miracles (and specifically the ones you want to admit, and not others) in.
The last part of the podcast is Schrock's positive account of how to respond to Hume (from a Reformed Christian perspective; I can't say I'm totally clear re. exactly what that entails, and there were some insider comments on the 'cast that make me curious to listen to more of them): the specific miracles accounted for by Scripture have to be given an appropriate hermeneutic account, i.e. what do they mean? They weren't just magic tricks designed to prove divine action, but have to be understood as... as what? Not purely symbolically; the podcasters think that these are historical events, and if they didn't happen, that undermines the whole religion. It sounds like they're saying that you have to accept the religion whole-hog; when you've internalized it, you'll understand why these particular accounts are privileged, divinely inspired, where the ones from other sects aren't. Though no one on the 'cast said "you have to just take it on faith," I think that's what the answer amounts to, with the following caveat: faith for them is not blindly accepting some proposition you don't understand, but entering into this whole strange world that puts you in a position to "get it," and if you're not already in that position, you're not going to "get it." It's difficult to describe this and not make it sound to outsiders (like me!) like brainwashing, but certainly the reflectiveness and studiousness of these guys belies that particular description. Some of the discussion on their site anticipates some of what I've said here and gives a flavor of the participants' response.