EAR post install hook to run a class?

Is there a standard way to tell an application server that, once it's installed an EAR, it should run a class contained therein? I'd like to be able to drop a configuration class into an EAR such that, once it's installed somewhere, it runs and sets up some local configuration.

If not a standard way, is there a Websphere specific way of doing this?

Or am I going to be limited to creating something that runs every time on startup, but does this configuration the first time only?

I would recommend using the @Startup annotation.
Of course it will run on each server restart, but you
could use it to do some other checks or things...