I first thought of the same suggestion that SkipVought had. This will work as long as you have spaces in between the words you want to "triangulize". If you have just a long string of letters - like "microsoftmicrosoftmicrosoft...", this method won't work - as soon as the letters hit the triangle, Word will shove the entire string below the triangle (the first line where there's enough space for the whole word).
And if you want to insert spaces... well, you might as well use them to make your triangle manually!
--Michael