This is just something that I whipped up in a couple of minutes ... It needs to be higher res to be smoother. Far from great but it should give a basic idea.

Well in Bryce you click on the symetrical lattice which is the almost top looking thing next to the mountain. Load the picture in. This will create a basic shape though it might need to be scaled skinnier and rotated. Since the file I was working was low res and kinda small the terrain is kind of jagged and choppy looking but if you work at a higher definition it will look better. Just remember white equals high points and black is low. The greyscale thing there is what I used.