texture

only if the map was compiled the old way and has seperated .wad file which u can edit by ur own as far as i know.

You can try to search for "detailed textures" for that map.

1. extract textures from THE map (textract or bspviewer)
2. look through extracted textures and find what you need to replace.
3. create 8bit textures with the exact same dimensions, name and extension (bmp/tga)
4. make a new map: box with playerstart, light and apply all new textures you created with the cloned names (at least once, create random objects to apply texture there).
5. start counter-strike and load your box map FIRST, then change to THE map.

Game engine will cache textures from your box map and ignore original textures from other maps, if those have same names. Cached textures will be used until you close cstrike client.

PS.This 100% worked back in 2009, I haven't tried it since, so there is a small chance it was patched or changed in the past 7 years.

spr1n is right. and it still works nowadays.