I don't think it's going to happen the same 'way' it does in TG2. In Vue, layers and alphas are a blending operation and are great for color and bump channels but I think (and I can't be sure because Vue crashes when I start horsin' around with displacements and layers) that you would get blending and your displacements muddied. I also think we could beat ourselves in the head trying to get renders from Vue that look like TG2 because after all, the two tools take different approaches and are different animals. Again, that's just my opinion.

However the same effects can be achieved readily in Vue and in some cases, might even look better upon close inspection...

The first way, of course, is to just use ecosystems and eco rocks all over the place.....but you are looking for the 'fake' rocks or the implication of such.

This second way is something I call 'outcropping' wherein you duplicate your terrain and lower it ever so slightly below the first one and change the color or mat or what have you. Then, with the softness way down, paint your terrain with the effects tool in the terrain editor. Start with pebbles and then use stones where you want them. Presto...instant rocks on your terrain. Also, you can use the raise tool and make other kinds of rock formations jutting out. 

It's not done like TG2 but the effect is the same come render time.