Is there a plugin for hotmail calendars
Go into outlook (hotmail) calendar and push "share" then choose the option to send a View only Link.  

Copy the "Import into other calendar applications (ICS)" link. 

On your mac, go to Calendar and subscribe. 

Write a name for your calendar and then enter the URL you copied from hotmail, substituting "http" for "webcals".  

Chose how often you want it it to refresh, what alerts you want, then enter and the calendar from hotmail will appear on your Mac!