Twiddle is a generic JMX tool. The only thing JBossAS specific is how it looks up the JMX server/connection (well, it does use things from jboss-commons, like logging). Change the JMX connection/server lookup lines (in the twiddle source) to do the lookup in the standard way and it should work.
Thanks for the reply, this is exactly what I've started doing, though it takes a while to replace everything, it seems like it should work. Will get back to this thread when I'm finished and let you know how it turned out.