Certainly possible. We can add it to the UI(Currently available in Advanced>UI settings page) options page and allow users to customize their toolbar.
The interface could be something similar to our existing tagger scripts UI
or Preferred releases UI
I can work on it and will try to make it in the 1.4 release 
apart from that, we also wanted to finalize a default layout for new users, thus my suggestion above
We have a ticket for it and its on my todo list [PICARD-353] Customisable toolbars - MetaBrainz JIRA