Was wondering why the wrong callback was being invoked - turns out you need to modify ProxyForJava.h like this:

@interface ProxyForJava : NSObject { void (*methodInvokedCallback)(const char*, id); char* (*methodSignatureCallback)(const char*); } ...

Note the new braces - they make the the variables members of the class, which is what we want. Otherwise they're globals or some such c-ish thing, which makes the results kind of hilarious (in retrospect).

Adrian