I think you could map the AST tree to XML then easily do refactoring using a standard technology like XSLT.
Then people could write refactoring snippets easily and quickly.
Furthermore you could easily store the AST Tree in binary XML form in the Database.
I attempt to write a patch to do this.
Logged In: YES
user_id=328291
Originator: YES
I came across this other project which could be instrumental.
http://sourceforge.net/projects/xpa/
by the way transmogrify compiles under java1.6 and appears to work with ANTLR 2.7.7
although the tests use old junit code, I would like a transmogrifier to update the test code from assert to assertBoolean