I assume, you mean the keys for something that can be found in nautilus' menu bar.
First: This doesn't work if the global menu is on. Since you can't disable it for nautilus on a per-window basis (for nautilus is always running in the background), you should either log in to a non-unity-session (like gnome shell) or disable it for all windows. (Here is a guide how to disable it). You have to change a setting in gconf-editor (which might not yet be installed on your system, but can be found in software center). The key you need to enable is:
Probably you need to log off and back on again to make this change take effect. Afterwards just point at the menu entry whose schortcut you want to change and press the desired keys. After all changes are done, you can turn on global menu again.