First we launch the game with the console enabled to find the name of the map we want. Then we download GCFScape and unpack it to our [...]/Steam/steamapps/ folder.
Then we use GCFScape to open up the desired GCF file and unpack the map we found the name of using the console earlier.
We then download VMEX and JRE 5 (Java Runtime Environment) which is required for VMEX to function. Then we install the JRE, unpack VMEX and use it to decompile the map which we then open up in Hammer.
Also, don't forget to give me tutorial requests!