If you need to convert iCalendar data to XML format you will either have to look for a special utility like the ICS File Converter, or do it manually - if you know how. ICS format (contacts not CAD) represents just a specially formatted text file, so you can create your own XML from it, you just need to use proper syntax. Of course using some kind of utility for ics to xml conversion makes it much more easier.
Open ICS file Open XML fileA web converter for ICS format