There are 3 possible locations for these textures.
They could be inside the bsp file. In this case, use bsptomap and decompile the bsp file.
They could be in a pak/gcf file. In this case use pakscape for the pak file and gcfscape to open the gcf file.
Or they could be in the counter-strike folder. If this is the case, there is nothing you need to do.