Key Commands and How to Listen for them

Assuming you are using Cocoa + Obj-C, if it's assigned to a menu item, just set the item to that key sequence in Interface Builder and set the action of the menu item to call your method in your code, or use nil-targeted action if it's a multi-document app (in this case connect the item to the First Responder object). The event system will traverse the responder chain until it finds something that implements the method whose name matches the one you set in IB.