How do I import into Outlook CALENDAR

We have a separate scheduling software outside of OUTLOOK. We would like to import some important Organization events from the scheduling software into OUTLOOK calendar. The scheduling software can export as excel, access, tab delimited, comma delimited, etc. And Outlook can import, but only as contacts and other, not calendar. We need to have import into OUTLOOK calendar. Does anybody else import into OUTLOOK calendar from their other scheduling software without having to rekey?