It looks like you're already pretty clear about how to call the relevant COM/OLE APIs from Perl, so really this is more of an Outlook API question than a Perl question. Your best bet is probably to go straight to the source in the source in the
MSDN Library and look under the objects/methods for Outlook. Specifically it looks like you would use the
Add method on the Items collection for your folder passing in the appropriate item type (probably
olAppointmentItem).