I remember seeing something in my Maya Help Section where fluid (fire & smoke) took on a specific shape because it was routed through a container or something. So, what about a container shaped like the word, when the smoke fills up the container it will look like the word. I hope someone has a better way though because this way sounds like a lot of work.
Don't be satisfied with what you can do but rather strive to do the things you can't do!
Exceed Expectations!