Wouldn't using listsinceblock require constant polling for receiving up-to-date information on the current transactions? Seems horribly inefficient, and wouldn't exactly be considered live.
Seems out of all of these options, editing the client to include a socket which spits out transaction information as it arrives would be the best option. May even go as far as to create my own, since I'd like to see a Node.js alternative (BitcoinJS didn't seem to work for me after hours of frustration) surface.
Oh well. Was kind of hoping for an easy-way-out that I could host on my own servers. Back to the drawing board, it seems. Thanks for the information, guys.
The creator of BitcoinJS is an
active member of this forum, you could ask him what needs to be done to bring it back up to working state, rather than implementing everything from scratch.