Somewhere on either PE or the Full Range Forum someone had a tutorial on doing just that. Search flush mount, I guess. You could also walk into a Woodcraft or Rockler and they would be happy to show you how to use brass collars they'll sell you for your router for your router.Doesn't quite come out in a few words but basically you're cutting a template that is 1/2 diameter of the collar away from the fit of the driver. Once the template is cut you mark it and save it and the routing is a snap.