the first step is to have winzip or winrar or packscape....
since winrar is a common utility, i will write the remaining instructions on that basis

browse your installation directory (mine is c:/program files/mapping/call of duty 2) until you get to call of duty 2/main/
in there you will see various .iwd files.....we will set up this properly

find iw_13.iwd and right click it --> copy
minimize the window and right click on your desktop --> paste

maximize your browsing window and click tools --> folder options
in the view tab uncheck the box that says hide extensions for known filetypes and click ok

now.....right click on iw_13.iwd on your desktop (CAUTION...DO NOT MODIFY THE GAME RESOURCE LOCATED IN THE MAIN/ FOLDER!!!!!) --> rename --> and rename the file to iw_13.rar and press enter (windows will give you a warning about changing extensions making things unstable...just ignore this and click OK)

double click on iw_13.rar (on your desktop) and winrar will unpack (expand) all the files and folders that are in there...locate the folder called xmodel and right click on it --> extract to --> extract this folder to .../call of duty 2/main/ ....you will need to browse for it in the winrar window so that it goes to the proper path

we can now check our installation folder to make sure that everything is where it should be....

click start --> my computer --> and browse to your installation directory (as noted mine is c:/program files/mapping/call of duty 2/)

open the main folder and look for a new folder called xmodel
if that is there then chances are you did it correctly

have fun mapping

StrYdeR