Until HomeAway supports iCal importing, calendar synchronization is only available to those with 5 or more properties through the use of the HomeAway Feed.
AS A RESULT OF THE NEW TWO FACTOR AUTHENTICATION INTRODUCED BY HOMEAWAY, THERE IS NO WAY FOR THOSE NOT ON THE HOMEAWAY FEED TO SYNC CALENDAR DATA WITH HOMEAWAY.
There is talk of an iCal import being introduced in early 2015 by HomeAway. If that happens, calendar syncing will return for those with <5 properties!