Its like a Homepage where you can edit it to have tabs customize the layout (e.g colours, text etc.)
and it goes into the root directory e.g say your link is
http://dubsteprus.co.uk/forum the homepage will go in the directory of the link
dubsteprus.co.uk
CMS will work better in my opinion.
In my opinion, something that is integrated with the forum will in almost all cases work better. Look at IPB content or whatever they call it.
You can do this to a certain degree today with the MyBB portal and a lot of free time, note.
OK, let's see.
Firstly, putting things in the root when the forum lives in /forum is a Bad Thing - firstly, not all fora are to be placed in a first-level directory (some may go three or four levels from the site root, although I'm not quite sure why) and secondly, the whole point of having a configurable forum-path is that everything lives in it.
I can see three, maybe four, ways around this.
First is the writing of a page that can be placed (or better (at least on Unix-type servers), symlinked) outside of the forum-tree and still work - presumably it would need the forum-path to be hard-coded into it, which in turn would mean it would have either to be auto-generated by the site first, or manually edited before use.
Second is encouraging those who want to use such a thing to set the forum path to the document-root, and making the "home page" one of the options for the forum home, much as there is currently the option between the forum listing and the Portal.
Third is a custom-written page that hooks into a MyBB install in a given path to provide the forum-related content. This is much like the first option, except that maintaining it is the responsibility of the site admin rather than the forum software.
Fourth would be simply redirecting / to /forums, and using the part of option two that doesn't require setting the forum-root. This could be done with .htaccess, or in the server configuration, or with some sort of javascript-redirection. This, too, is the site admin's responsibility, and like option three it doesn't affect anything in folders, only the site index (which is to say, the page one gets when going to the site root)
The other thing is that as far as I can see this would duplicate the functionality of the Portal, which is already built in to MyBB. Correct me if I'm wrong about that, beyond the fact that the Portal can require some heavy configuration and plugin-installation to get it behaving the way one wants, since that would doubtless apply to a "Home Page" as well.
Unfortunately, I think this is another of those things where a small group of people would use it -but not many at all. Just because vBulletin or IPB, or XenForo do it, it does not mean that MyBB needs it.
Edit: Sorry, vB doesn't have this AFAIK. I got confused with the replies.
Isn't there a free mybb Cms being developed? that should pretty much cover this I imagine though I haven't got a clue when it'll be available.
Your best bet is just use a Cms or knock up a website yourself, I can't really imagine that someone would spend months and months developing something like the OP requested and even if it was to be done I can't see it being available for free as the developers would want something in return for all the time and effort.
If you really want some kind of Cms to do what you want then you're probably better off paying a developer to build you a custom Cms or something....would look so much better IMHO.
Or better yet an advanced API that could allow information to be pulled to a custom page?
MyBB will have an API.
Although, tweaking the portal design to be more like a CMS homepage wouldn't be a terrible idea.
You can already take the portal and rename it to index.php and put it on the home directory. Then you'll just have to edit 1 line in portal.php to have path to forum, and edit a couple templates to change image directories in the header.