Here's a Screenie of Clay's Fire that I tweaked with altitude sensitivity. It seemed like a no brainer to me, but it's a bit harder to use than Clay's Fire by default. As for adding a pic as a transmap, it's very possible. Add the pic to the second slot in the Picture Source Editor (you can leave the first slot blank if you just want a transparency map), and that will affect transparency (or bump), it depends on where you assign your dots. The basics of it is that the second slot there is the alpha channel.