[philadelphia killing mach]

I have a map i downloaded. I wish to retexturize the interors (walls, doors, floor, etc). It looks like the map uses all textures from original MOHAA pk3 files/textures. To change the textures would i :

• 1. extract the script for the map
  2. follow the directory on the script
  3. extract the textures from my mohaa pk3 files
  4. retexturize the .tga files
  5. rewrite the directory of the script to go to the textures folder i would make in the new .pk3
  6. put my retextured files into the texture file i would create for the map's .pk3
  
  if this is the way to retexture a map, how do i crack the .bsp (the only file that is in this map's .pk3)
  
  if not, how can i retexture a map ?*
  what tools ? i've tried many so called .bsp editors (including scorpio's and the pk3 manage editor on here)
  
  
  
  *yes, the original author is going to get full credit for the map.