Editor keys are using whatever keys are assigned by FSX to the Slew movement keys, we don't check actual keys, we intercept the various Slew events, which is the correct way of doing it, because those keys might be redefinable in FSX. Didn't know that FSX doesn't allow you to redefine such keys.
In any case, the Numpad is usually accessible on those keyboards that do not have one, by pressing some additional key (usually the Fn key) together with a group of keys in the middle of the keyboard, that typically include the Numpad layout text printed on the keys with a dimmer color.
If your keyboard doesn't have this feature, which would of course prevent to use the regular Slew mode too, I suggest using an external USB Numpad.