CAD-software isn't meant to be used for stuff like flames, that's why it is so hard to do. The easiest way would be to make flames with Photoshop or Paint Shop or a similar program, then you save the flames as a jpeg.
In your cad-program you open the jpeg-file and you can then easily draw over the outlines of those jpeg-flames.
Haven't done that yet, because I don't use flames, but that's basicly the same as I do when turning a 3-view into a dxf-plan.