Right now there are no extension points for the jpa-new-entity command, so unfortunately you'll have to create your own UI command in your own addon and with a different name.
You can do the same as JPA: New Entity does now, and change the field name returned from PersistenceOperations.newEntity using the Roaster API.
It would be nice if you could open a JIRA in Forge - JBoss Issue Tracker so we can investigate a way to support rebinding command names.
Thank you very much and sorry for the trouble.
Here is another hint: You could implement a CommandExecutionListener and in the postCommandExecuted method, check if the JPANewEntityCommand was executed and apply the necessary changes.
Let me know if you need any help
Thanks for the quick response.