Hey Patrick,
I guess this could be done with a bit of a custom code.
I imagine something like this.
Create a special category for these kind of events.
Do a template override for the list view and month view. (And any other views you may need, possibly photo, day and week if you are using those.
In the override check first the category of the event and if it’s a match, then don’t put a link to the event, so ppl cannot click and go there.
The single event page will still be there though, just not accessible through the calendar views.
Instead of categories you could also use tags or custom fields.
Would this do the trick?
Andras