Umm....No. See, I already have an "equirectangular" (at least, it's a 4096x2048 image that tiles horizontally) heightmap made by plate tectonic simulation that's been tidied up a bit. Now I want to erode it, but most of the erosion software does not preserve the tiling on the x axis, except fractal terrains, which has rather limited erosion tools, and wilburs precipiton erosion, which I have now learned can be made to tile horizontally using the wrap option.

I'm not too concerned about spherical displacement mapping in 3d software (that's easy, if I wanted to do that), I just want to edit the heightmap in software that knows the heightmap should tile horizontally.