I did many attempts at getting it to hook, but never got it. Pausing watcher and resuming at different moments of loading Witcher kind of finally got a hook. Oculus grey lined space started loading, but then Witcher just silently shuts down.
Reinstalled Vorpx, changed Vorpx setting while in a working game. Nada :(
I use GOTY edition on GOG.
(The pause watcher helped with Bioshock Infinite though)