mods are installed with the JSGME tool
it stands for jonesosft generic mod enabler
get it here:
http://www.subsim.com/radioroom/showthread.php?t=123908
install by placing the exe file into your programs files "ubisoft / Silent Hunter Wolves of the Pacific" folder then click on it, thats it and you can remove the exe file afterwards or delete it or leave it there but jsgme doesnt need it so your finished with it.