I remember reading a post by Nick Darnell that a rich-text box is in the works, and could possibly be included with the 4.5 update (don’t quote me on , but it is coming soon :)). So that will help you quite a bit once that is ready, but right now there is no easy way to do currently.
I see you have already posted in the UMG Doc Thread as well, here is a response to a similar question: