Nope, not possible, might as well create a new game if your gonna go to the trouble to create a multiplayer Morrowind. Yes, it would take THAT much effort to do, and if you think logically if it was possible wouldn't the game creators have added that in? Not to mention the fact that if you are system linking why would you keyboard communicate anyway? As for the script I doubt it would be possible and once again, if you are system linking why would you need a keyboard? Do you mean X-Box Live, because if you do then that too is impossible. Are you using that free alternative to live? Sorry if I am coming off as harsh but these messages are fairly common on most Morrowind Forums.
-Kyrin