
To my knowlege. there is no way promote the Amiga's Workbench screen to the OpalVison card. Only applictions written for it will run on it. There may be newer tools on Aminet that I'm unaware of, though. Check them out, if you like.
;-) CyberGraphix is the way to go, if you're looking to promote Workbench and applictions to 24-bit screen modes. There are utilities on Aminet that will promote older applications to custom screen modes, too.