KeyRead V2.0 is most effective for older Mitsubishi FX series controllers. It is widely considered the "proper" tool for accessing password-protected logic when the original code or password has been lost. Mitsubishi FX1S, FX2N, and FX1N series.
If you are using a diagnostic tool with a "Keyread v20" equivalent function, here is the standard workflow for programming a key: keyread v20 mitsubishi best