Maybe this can be of help:
http://www-10.lotus.com/ldd/dominowiki.nsf/dx/Getting_Domino_calendar_view_data_for_a_range_of_dates_and_getting_a_URL_for_specific_events
There's plenty of information about the ?ReadViewEntries command that returns JSON or XML on google:
https://www.google.no/search?q=lotus+notes+readviewentries&oq=lotus+notes+readviewentries
Another way is to create a web service. You should be able to find information about this on google as well.