I assume you know where they are located. If not, they are in your CoD root folder /bin/maya.
Tbh, i dont really remember where i put the plugins, but i think i stored them in "my documents/maya/8.5/prefs"
Im not sure though. Just try putting it in that folder and loading them, i apologize if it wont work. If that is the case, then i shall find out where you need to place them in order to load them.
EDIT: I just googled for a tutorial.
http://wiki.modsrepository.com/index.php/Call_of_Duty_2:_Maya_Plugins_DocumentationGoogle answered my call with this answer
It is outdated but it might be helpful if what i posted above doesnt work.