Thinking outside the box here.
First of all wireless sync is out of the question and would have to be disabled.
SO in outlook you have your Chief of Staff (CoS) add the CEO's mailbox to his (assuming you use Exchange) so the CoS has rights to the mailbox and can see the CEO's calendar in his mailbox.
Then in Intellisync you add the CEO's calendar to the list of synchronized calendars. Set the synchronization to go one way (Import) to the handheld. So on the CoS's Blackberry he would see all his appointments and the CEO's. He would have to synchronize everytime, but it would be sort of a workaround.
Off-Topic I have gotten 4.0 and another users calendar desktop sync'd to work as well in this similar fashion. We have admins that want execs calendars on their Blackberry's. While RIM says it is not supported does not work, it can with the right settings and process.
Let me know if you need further clarification. Blackberry Theory should be a Meet the Experts Seminar.