How could I have a 'done' button on all pages not only the last one?

I put all important fields on page one and have optional fields on page two and lot of user stop by making 'save' on the first page. As I am using locks on page edit (Content locking (anti-concurrent editing), http://drupal.org/project/content_lock), I would like users to be sure not to stay on an edition page, locking it for other users. For tha I would like a 'done' or 'save & view' button on every page, so the lock would have better chance to be released.

How can I do it ?