I have never seen a tutorial on that. The only time I have ever rendered flames in an image, it was done in post. You can find chroma keyed flames on YouTube and google. I don't know if flames can be done effectively in Poser. Of course, the materials master bagginsbill would know how to do it. As far as animation goes, I'd do it post.

If I had a nickle for ever time a woman told me to get lost, I could buy Manhattan.