Sorry, there is no real instructions in that page indeed. Let me explain then.
- Browse for HKCU\Software\Patchou\Messenger Plus! Live\GlobalSettings
- Right click in the section where values are displayed.
- Select "New>DWORD value"
- Name the new value as "SafeHook"
- Its value will be 0 now, you can leave it like that.
Now exit Messenger and restart it. If it causes problems with Messenger, you can set it as 1 again or just delete that value.