I've been having some back-and-forth emails with RV-D-B, who's been trying (ultimately successfully) to build Cocoon with eXist as a block, based on our documentation of our script, and also trying to integrate FOP 0.95 into it. He's succeeded in building Cocoon, which is good to know -- it means the approach we took last year continues to be practical -- but has given up on FOP, mainly because it's not terribly important to him, since it has a key failure (footnote rendering) which makes it useless for him. For us, FOP would still be extremely valuable, so I've been pleased to see this page and this page suggesting that others have succeeded in doing it. I think it would be well worth trying. In the meantime, when I have a moment, I'd like to try re-running my original build script to see what happens.