I would like to use the right-Alt key (Alt Gr) as ⌥ key. These are modifier keys right of the spacebar on MS 4000 Keyboard: . I currently have the Application key mapped as ⌥, but Alt Gr would be less clumsy.

If it matters, there is an Alt sticker on my MS 4000 (instead of Alt Gr), and currently my Alt [Gr] doesn't function as any modifier key. I've already looked in KeyRemap4MacBook and the question AltGr keyboard shortcuts on MacOS?.