You will have to edit the
.nib files with a text (or xml) editor. First make a backup of the app (especially for Finder), then go into the bundle contents and find the
en.lproj. This will probably be in the
Most likely, this file will be called
MainMenu.nib. However, Finder's is
MenuBar.nib and some apps, like Firefox, won't have one at all.
The nib file can be converted to XML with
plutil -convert xml1
<filename>. Then you can open it in the text editor of your choice. Just command ⌘+F (or control ⌃+S) for the menu name you want to change. It should look something like this:
Edit the string at the top. This is actually the Interface Builder connection between the menu item of that name and the Objective-C selector/method that it calls. Save the nib and relaunch the application (with Force Quit or
killall for Finder) and you should have the different name showing up.