How to implement key equivalent for NSSearchField

I have a Cocoa application I am building which contains an NSSearchField control. I want to enable a keyboard shortcut / key equivalent so when the uses presses COMMAND-OPTION-F, the search field gets focus.

However, after much searching, it is not clear to me what the best way to implement this is. There is not an option to set this for the NSSearchField in Interface Builder.

Is the solution to subclass NSSearchField and listen for the keyDown event (and then see if the key equivalent is pressed?)

You can always add a menu item with a key equivalent of ⌘⌥F i.e. CommandOptionF. In the menu's action, just manually make the search field the first responder using

[window makeFirstResponder:searchField];