Open your WoW folder.
On the top of the folder window you will see:Organize Views Open Share and Burn..
Click organize, then click Folder and search options.
In the new window click the View tab.
Under advanced settings make sure where it says Hidden files and Folders that you have "Show hidden files and folders" bubbled in.
Right under that it says "Hide extensions to known file types"
Make sure that box is not checked in..
Now go rename the patch so that it will have .MPQ at the end, case sensitive.
Now start MEF press f8 at login screen and have fun with your model edits! =D