Once you have the frameset in place all you have to do is add online booking links to your main menu and other pages as you see fit. Those links will point to the new frameset file on your server.
Just think of the frameset as an additional page at your web site.
For your clients, the frameset represents the beginning and end points of the online booking process. The only time they will see BBU branding is when they visit their personal appointment center. Your own branding will be seen on all other booking pages.