Ready to ship!
Eventually I have decided to go for a new plugin having a dependency with the existing deploy plugin. This, in my opinion, is the best solution because, being WebSphere a proprietary product and being some jar not redistributable there is a needing of a little extra configuration (just copying a couple of proprietary jar on the classpath) at the end of the plugin installation. Anyway more details will be on the wikis (either my personal one and the one of hudson if I can publish my plugin) once I got the right to check-in on the hudson java.net repository.
So hung on for a little while....