Terrain editor - painting textures on walls/cliffs orientation

This is a random question, but... I noticed in the terrain editor that if you use the set height tool to create canyons, the texture that is placed on the canyon wall will look mega distorted because it is oriented to the ground and not the canyon wall you created.

Is there any way to paint textures oriented to the canyon walls you create with the terrain editor, rather than the ground?

The problem is that the textures can only be mapped based on the vertices, for the steep cliff faces this causes the vertices to be stretched which makes the textures on them to be stretched. I know 1 common solution for this is to actually create models which you use in conjunction with the terrain for the cliffs, this way you can control mapping better and in general make nicer looking cliff faces.

Would like to preface this answer with the fact that I have only used the actual Unity terrain system briefly since I mainly work in Unity iPhone which does not yet support terrains; but this is based on my general knowledge and experience with terrain engines.

You may consider using a shader that solves the problem of distorted textures on walls/cliffs of Unity terrain:

However, it tequires a shader model 3.0 (which is unavailable on mobile platforms).

I tried to use an imported model but then, since its now aterrain, when i wanted to put trees in it became quite a task! (cause its not a terrain)
is there a way to convert a model to a terrain? cover the model with a terrain or any other solution?