http://www.celestialheavens.com/forums/viewtopic.php?t=9704
http://www.celestialheavens.com/forums/viewtopic.php?t=10078
http://www.celestialheavens.com/forums/viewtopic.php?t=10240
GrayFace, who makes unofficial patches for these three games, has been challenged by a Codex poster to add free mouse look to the games. It seems that he has done the deed in just a week. Damn, that was fast!
Anyhow I tried it myself with my GOG Might & Magic VI copy, and it works fine. You need to install the unofficial patch for the game, and to download the mouse look setting file. Then you copy the content of the file to your MM*.ini file.