Thanks for the tip . Sadly, since this is a *server*, the app runs as a background service (using the start/stop daemon) and I've no idea how you could send particular characters direct to the input stream. I also strongly suspect all output would disappear - the standard logging libraries only log log messages, not stdout and stderr.
(I'm sure if I spend a while digging in manpages I could find a way to re-route stuff to/from the daemon, but it's just not trivial)
Not sure how possible this is with your current setup, but JDK 1.5 includes some new profiling/analysis tools including jstack, which will perform the same function as
ctrl-\, except you can attach it to an arbitrary pid.