Well, if we know that today they come from people who were still alive, I think it is only sane to say that the Church (in her right state) would never permit Catholics to support such activities by receiving the organs harvested from live persons. It would be equivalent to going to the black market, where I hear they do the same... in some cases harvesting from a perfectly healthy inmate (I heard this of a communist country) when they arrive to meet the buyer.
There is, I think, however, something far worse going on here. That is, people have developed this morbid fear of death, wherein they are willing to do just about anything, no matter how painful, expensive, ethically correct or moral it is, just to stay alive. What ever happened to making a good confession and resigning one's self to God's holy will? Is the thought of submission to God's providence that distasteful?
People shun that kind of thinking as being backwards, and indeed, you can't just not take care of your body. We do have a moral responsibility to accept ethically correct cures which do work. But if the cure is unethical...?
The ends don't justify the means. This is a widely accepted error today, but it is an error. You cannot just do "whatever it takes" that good may come of it. You cannot do evil in order to obtain good. If my liver gives out, and my option is taking one, the absence of which murdered another human being... Well, it may appear I have a choice, but I think, in the sight of God, it only APPEARS that way. If I love God, I cannot promote murder of anyone, on any scale (eg, even embryos), even if the doctor thinks it's just fine to do so.
These people are dying horrible deaths, because there are a LOT of selfish people out there, who don't mind doing something unnatural and unethical in order to live... and for what? So they can sleep around some more? Have another party? Commit a lot more sins? Go to Florida? Buy that big screen TV?
What is life? Is it a party time? Is it a place to have good, fuzzy feelings with friends and family, seeing sights, blowing cash and collecting material things? Or by any chance, are we here to save our SOULS? To get to heaven? To live and die for and in Christ?
Even if we're "nice" ... even if we're "good" (according to the world, which translates that you like animals, you're a vegetarian and you recycle your newspaper)... even if we have friendly chats with our neighbors over the fence in the back yard... this life is not about that. This life is about being a saint, and one part of that is following God's law and doing the right thing, even if we die for it in consequence. It's part of accepting divine providence. Yes, if you're not well and there's a cure that is ethical, you're bound to take care of your body according to Catholic teaching. But if there's no ethical cure, then hey... it's divine providence. The patient will say, "yes, but if I take the organ, I'll live!" Well, if the martyrs had taken a sword to their executioners, THEY might have lived. But would they have gone to heaven for doing that instead?
Our lives belong to God. We BELONG to God. (Our dear, beloved family members... even THEY belong to God, NOT to us!) And He will do with us what He knows is best, not what we think is best. And if it's better for us to die at a particular time, and instead we cheat death by unethical means, we've really cheated ourselves... sinning in order to live.
People need to get back to an appreciate of what life is, and what life is about. There ARE worse things than death! There's eternal death! And if we do everything we can within moral limits to live, and we end up dying... hey... that's divine providence. And it's much better for us, because it comes from an all-loving, all-knowing God.