The advice you got on that thread is right on the money. If you didn't understand it enough to implement it, you could have asked for clarification instead of starting a new thread on another forum without telling us about the advice you already got.
Study the section of the Swing tutorial that deals with How to Use Key Bindings and you'll be able to do this yourself.
I would question the rationale behind this. What practical difference does it make whether the action is triggered by releasing, not pressing, the <Enter> key? What's different about your application that requires non-standard behavior?