the morrowind codepatch beta allows "swift casting", see http://www.tesnexus.com/downloads/file.php?id=26348. you also need the latest official release of http://www.tesnexus.com/downloads/file.php?id=19510
note however that it will cause major clipping depending on weapon length and the size of your shield (if any). best used with an animation replacer, but there are very few (almalexia spell casting is an option, but has it's own flaws)