There's good news and bad news.
Good News: I got the Single Player CubeChange working!
Bad News: Apparently Paul doesn't allow client mods on servers for the 20120627.
I don't think that's true. I think your definition of a client mod might be incorrect.
CubeChange is a back-end set of scripts... so it has to be on the server in multiplayer. It's just that in single player, the "server" is running locally and without a network connection.
A true client mod would be a local console command that calls into the world object to set blocks that way.
On the server, I already have the ability to clear entire leafs, I just don't have the time to walk around and do it 90 times or whatever... nor do I think such world-destroying behavior should be as easy as "Beg Paul a bunch". Even though the starship enterprise that someone added is pretty cool... that player destroyed plenty of the world up until that point. And created many odd and strange things besides.
Anyway, part of me feels fine making people work at such huge efforts... everyone will appreciate it that much more. The stuff that has been created by Rayblon and crew is that much more impressive precisely because it was created by hand.
All that said, if a client-side scripter grows out of this dilemma then that's ok, too.