In the To Do pane of NoteBook’s Preferences, there are a few options (page, Notebook name, etc.) you can choose to determine to which calendar a Notebook’s action items get synced. I think this might be what you are looking for.

I also want to sync to my iCloud calendar, but as you mentioned that it might be set in the ToDo preferences area, that is not the case. You can only choose ical or entourage.
Any additional advice?

Mickey

You can sync to iCal. Then iCal gets synced with iCloud. I’ve not tested this out, but from the reports of others, I believe this works.