I am also somewhat suspicious about whether the solution described there has ever been tested in the published form, since (as pamplemousse_mk2 already pointed out) the use of iCoeEnv->WsSession().EventReady() isn't actually a good idea, since there is already a client for the standard RWsSession.
Has anyone succeeded in using this method so far? I assume that there are some additional restrictions as to what applications actually get this notification, but this should probably be described in this solution, and the iCoeEnv->WsSession().EventReady() bug should be corrected.
I think if you need a notification of keypad unlocked events you can detect user activity and check every time if the keypad is locked, or have a timer ... change of focused group is not enough.
We had some special needs to catch the notification event, so we purchased support case and then private api request.
forum.nokia have a solition, but I think it is still not available to the public.