Creating a search scope from different lists across site collections

I got two site collections, and under each I got a subsite with a calendar list:

site collection 1:
http://siteCol1/subsite1/Lists/Events/calendar.aspx

site collection 2:
http://<siteCol2>/subsite2/Lists/TeamCalendar/calendar.aspx

I'm trying to create a search scope to be used a results page found under site collection 1.



Should I use a site collection level scope or a farm level scope for this?



What would my scope rules look like then if I only want the results to show the event items found within these two calendars and nothing else (I don't want to show list views from these lists as well)

I've tried creating a shared scope but no items are showing up.