Virtual Textures

Virtual Textures / Clip Mapping / Megatextures

1 : Is it possible to use the technology of virtual textures into the main tools of the program for terrains or just meshels ?

2 : Is it possible to implement using the methods available to the # in the context of the engine ?

3 : In an extreme case, Is it possible to implement with help Unity SDK ? (win or mac)

PS. textures res is 20k*20k or 40k*40k and not a power of two