Dan, many thanks again!
I commented out the following line in Event.inc in method getEvents() and now pending events show up when a user goes to the "Edit events" admin page, allowing the user to edit approved and pending events:
# next unless ($event_details->{$s->{'event_id'}}->{'approved'});
Note: this change probably won't work for most people -- as pending events will probably then show up on the calendar!
I've made previous modifications to calendar.pl and default.html (based on other useful posts) such that the administrator will see pending events on the calendar (in a different color) -- and users who can't approve events won't see them.
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See some of my modifications to CalendarScript at
http://www.prayforoneanother.org/cgi-bin/cal/calendar.pl