Getting PWI items in game

I'm just starting with the pw editing stuff, and I'd love to learn how to do more client-sided edits. I tried to get some pwi wings in-game. But I ran into some problem. Maybe something is wrong with the way I'm trying to do this, but what i did was:

-Open the folder which had all the files off the pwi wings in it. (.ecm, .ski, and things like that)
-Copy them into the folder of the pw-my wings i tried to swap them with.
-Give all the pwi documents the pw-my wings' name (For example, I replaced pwi's "name "Wing01.ski" Into pw-my's "Wing02.ski")
-Delete the old pw-my files.
-Repack my models.pck
-Replace it with my old models.pck

Once I do all this, I just get a couple of invisible wings.
Can anybody please tell me what i'm doing wrong?

Thanks in advance!