I've developed a source code parser (in Jade) that takes a schema (or class, or method) and parses it into an abstract syntax tree which you can then manipulate. This can then be output as a .scm file and reimported. We use it to do bulk changes to code that would otherwise take too many man-months to do by hand. (It also makes simple peer reviews easier, such as checking "are all iterators deleted in the epilog"). The only problem at the moment is that it gobbles up comments, which I'm currently working on fixing. This would achieve what you want but unfortunately it's not mine to give away. It goes to show that this in indeed possible, and the primary mechanism is to do schema export/import.
If the method names are unique enough, could you use standard shell tools like grep, sed and awk on the scm file?