Indico allow you to programmatically access the content of its database by exposing its events through a web service, the export.py script.
A typical example of how to use this script is:
http://my.indico.server/tools/export.py?fid=2l12&date=today&days=1000&of=xml
where:
fid is the category from which you want to extract the events (can be a + separated list)
date is the starting date of the event (format: yyyy-mm-dd or today)
days is the number of days to export the events (starting on date)
of is the output format (one of xml, html, ical, rss)