As Fil said, actually *simulating* this would be difficult, but simply getting a similar effect might not be so hard. If you got the right displacement working - and you could even use an imported image, to get it just right - it might work in WM. You're more likely to get reasonably good results in another application though, likely one that has a "fibre" or "painting" filter, as Fil mentioned. There are actually quite a number of applications, some of them even free, that have such functions. Take a look at Dogwaffle and The GIMP for example (I think the free versions of both can do similar things). What you would probably do is create terrain, import it into the imaging app and filter it, save it in a format to be imported again in WM then use the altitude constraints and blending to get it looking right. You may also want to use some erosion, different blending methods, etc. to get the right effect.
I am very interested in seeing the results of this if anyone gives it a shot. I probably won't have time to play with it any time soon, but post results here if you do.
- Oshyan