Hi Elisa
	Yes here is what we did:
	1- we first have some ICS layout file (ics.php file in the layouts folder)
 
BEGIN:VCALENDAR 
VERSION:2.0 
PRODID:-//hacksw/handcal//NONSGML v1.0//EN 
BEGIN:VEVENT 
DTSTART;TZID=:
DTEND;TZID=:
RRULE:FREQ=
 
SUMMARY: 
LOCATION: 
DESCRIPTION: 
END:VEVENT 
END:VCALENDAR
	2- at the record time fo the event we launch an aftersotre code:
	// No Direct Access 
	defined( '_JEXEC' ) or die;
jimport( 'joomla.filesystem.file' ); 
	$app=JFactory::getApplication(); 
	$isNew=$config['isNew']; 
	$event=JCckContent::getInstance( $config['id'] ); 
	$ics_file='images/event/ics/' . $config['pk'] . '/' . $event->get( 'alias' ) . '.ics'; 
	$ics_layout=new JLayoutFile( 'ics' ); 
	$ics_content=$ics_layout->render( $fields ); 
	JFile::write( JPATH_ROOT . '/' . $ics_file, $ics_content ); 
	$event->save(
'more',
array(
'ics_file'=>$ics_file
)
);
3- in the content view we have a before display code:
$id=$fields['art_id']->value; 
$title=$fields['art_alias']->value; 
$url=JURI::root(); 
$domain=substr($url,7); 
$label=JText::_(iCal) ; 
$ical="<a href='webcal://".$domain."images/event/ics/".$id."/".$title.".ics"." ' >$label</a>";
$fields['ev_event_lien_ics']->html=$ical; 
$fields['ev_event_lien_ics']->value=$ical;