You'll have to define the textures as variant textures of a surface. That means, go to:
tools/textures/select terrain which surrounds runway/select surface that surrounds runway/edit/press the lower add
seek for you textures there.
Place them by pressing only the texture fill. This means the runway will have the properties of the terrain which surfaces variant it is. Or sort of. The sound atleast will be, I think the hardness and dust values stay ok. But you can use cfgSurfaces in the config to make sure.
I took the runway tex from Nogovas northern airport and turned them around in photoshop... just use texview to convert to tga, then twist 'em, then convert back to .paa/.pac. I turned them so that the runway is north/south, that's the only working direction.